HoloAudio May KTE DAC with HQPlayer Review

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WGH

HoloAudio May KTE DAC with HQPlayer Review
« on: 31 Jul 2022, 10:30 pm »
The HoloAudio May KTE is a R2R NOS DAC with an A+ rating in Stereophile's Recommended Components. The positive reviews of the May and the more affordable Spring are all accurate. The HoloAudio DACs are the real deal but unfortunately, at $5,598 for the May, not the affordable giant killer everyone is looking for.

The May is often compared to the Denafrips Terminator Plus because both are R2R DACs and the price of the two used to be close. The Terminator Plus was $6,500 a year ago. I have seen only one review where the reviewer preferred the Denafrips, there are probably more. At this level system synergy is the determining factor, one is not better than the other, only different. The Denafrips Terminator Plus current price is $8,849, so HoloAudio DACs might just be the fabled giant killer.

Housteau's posted a well written review of the May, since it sounded so good in his system I guessed the May would sound great in my more modest setup.
https://www.audiocircle.com/index.php?topic=179643.0

My system specs can be found here:
https://www.audiocircle.com/index.php?action=systems;system=821


The other three reviews that convinced me to take the plunge was Stereophile, GoldenSound and New Record Day. Check them out if you are unfamiliar with HoloAudio.

Stereophile Denafrips and HoloAudio Spring review
https://www.stereophile.com/content/gramophone-dreams-60-denafrips-terminator-plus-denafrips-gaia-holoaudio-spring-3

GoldenSound HoloAudio May KTE review part 1
https://youtu.be/Wa3sOSRa-U0

Golden Sound HoloAudio May KTE review part 2
https://youtu.be/mHcfgQtlnP8

New Record Day HoloAudio May KTE review
https://youtu.be/HPtsWvhjLxA


Both the Spring and May actually have two DACs inside: the R2R NOS DAC supports 44.1 kHz to 1.536MHz PCM output, the separate DSD Discrete Resister Ladder DAC supports DSD64 to DSD1024 natively. The HoloAudio DACs do not convert DSD to PCM before processing like the Rockna, Denafrips and other DACs.

My previous DAC was the excellent Van Alstine Fet Valve Hybrid. It works perfectly, sounds great, but only goes up to 96 kHz and doesn't do DSD. It is also 10 years old so it was time for a change.

The difference between the AVA and HoloAudio is subtle, more cumulative than night and day. A little more space, low level detail is enhanced, more bass but if you have a sub a 2 dB increase in volume would almost sound the same. Where the HoloAudio DACs excel is hi-res audio and DSD. Details, echoes, sounds buried in the mix are clearly audible when compared to 16bit/44.1 kHz recordings using JRiver. I have Carmen Gomes album Ray! in 768 kHz and the clarity and “in the room" feeling has to be heard to believed.
https://www.soundliaison.com/index.php/studio-masters/856-ray-carmen-gomes-inc




The original recording format of Ray! is DXD 352.8 kHz, analog mixed and mastered to tape using a Studer A80. All other formats are converted versions of the original. The Sound Liason  promotion email I received said:

“The RME company is highly regarded by audio professionals.

”Before we started working with Merging, RME was our converter of choice. So when we got offered to test the RME ADI-2 FS, a compact 2-channel AD/DA converter we gladly approved.

”The first comparison with our Merging Anubis was immediately positive. Lots of definition, a beautiful soundstage with perfect placement. And after powering it with the Ferrum Hypsos external power supply, a sense of calm and control was added to the experience. This is clearly a serious converter. The RME has a maximum sample rate of 768kHz. To really see what the RME ADI-2 is capable off, we created a 768kHz/24bit file straight from our Studer A80 tape recorder playing the ¼" reel to reel master tape from our latest release [Carmen Gomes Inc. Ray!].

”Listening and A/B comparing with the Studer the result is quite convincing. In our opinion the sound is very close to the analog master tape."





This is where I got spoiled.

Hi-res recordings sound so alive and real that 44.1 kHz now sounded flat and unexciting, like a blanket was thrown over my speakers. Now that I know what is possible it was time to try out HQPlayer.
 

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #1 on: 31 Jul 2022, 10:30 pm »
HQPlayer
https://www.signalyst.com/consumer.html

Almost all DACs are locked into a sound: detailed or laid back or analog-like. The Scott Nixon DAC wasn't detailed at all, probably a good thing in 2006 when CDs were mixed bright and sharp. The AVA Insight DAC sounded warmer and not as bleached out after the Burr Brown OPA627AP linear IC swap.

A few DACs like Auralic, Aurender, Ayre Acoustics, dCS, EMM Labs, Mytek and PS Audio PerfectWave DirectStream have a field-programmable gate array (FPGA). Some upgrades update features; others, like the PS Audio affect the sound too.

Stereophile's Jim Austin wrote:
"Compared to earlier [PS Audio PerfectWave] firmware versions, Huron may have a bit less of the obvious warmth that has led some listeners to characterize the DirectStream's sound as "analog-like." So it's possible that your Huron-updated DirectStream DAC will sound less like your record player. Are you okay with that? Some may regret it, but to me—and I hope I don't lose cred with vinyl lovers—it was a clear improvement, and in line with Smith's last observation: "the bass gets less emphasized and doesn't call itself out, but everything from bottom to top sounds more time accurate, and hence there's a little better PRaT."
https://www.stereophile.com/content/ps-audio-perfectwave-directstream-da-processor-huron-firmware


HQPlayer enables the user to tweak the sound like FPGA through the combination of 30 digital algorithms and 15 dither settings. JRiver sounds different than Foobar2000, Audirvana or Roon. The digital filters and dither choices each manufacturer picks subtly change the sound. HQPlayer bypasses the player’s decoding engine and lets the user choose what sounds best on their system. 


HQPlayer Desktop is made by Signalyst and includes support for: HQPDcontrol for Android and iOS; HQPWV remote for tablets, smart phones, etc; Roon; muso music database; and Alchemy Desktop, an audio library touch friendly interface.

Signalyst also makes HQPlayer Professional which is intended as a mastering post-production tool for producing high-quality final distribution files in various formats. The professional version does not have the Roon, remote or library support, its function is to make and export high quality hi-res music files similar to the RME.

Because HQPlayer Desktop is based on a professional production tool it is priced higher than music playing software like JRiver. HQPlayer Desktop is available for Windows, iOS and Linux operating systems and costs $223.50. The trial version plays for 30 minutes at a time.


Simply put, upsampling 44.1 kHz is a revelation. All the low level information buried in the mix can be clearly heard. Space surrounds musicians and effects take on a new life.


An example is Shaun Colvin’s 1996 album A Few Small Repairs.
Halfway through the first track “Sonny Came Home”, Shaun accompanies herself in a quiet background chorus.
The chorus in the upsampled version is ethereal and floating rather than a flat L-Center-R presentation.



Percussion and bells in the excellently recorded Planet Drum by Mickey Hart are sharp, clear, shimmer and hang in the air without any added harshness.
The bass drum in the track “Temple Caves" rolls through the room with authority.
A couple of friends came over for a listening session, everyone was quiet and focused on the music but when the bass drum hit one of the guys was so surprised that he exclaimed WOW.



Albums that have actual dynamic range with low level information are enhanced the most.
A poorly made studio recording remains horrible.
Nothing can help Jeff Beck’s Blow by Blow, I think upsampling made it sound worse by exposing its flaws.
The SACD of Blow by Blow sounds a lot better. DSD has a slightly different presentation; I would define it as mellower.


Because HQPlayer can produce high sample rates the temptation is to think that more is better, you are only limited by processor power and DAC resolution. My sweet spot is 352.8/384 kHz and DSD256. Higher sampling rates are not as musical to me.
There is no wrong setting, the sample rate and upsampling filter used is system dependent.

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #2 on: 31 Jul 2022, 10:31 pm »
HQPlayer Desktop is the opposite of plug-and-play. At first the 21 inputs, 30 digital filters with up to 16 million taps and 15 dither settings seem daunting but many are optimized for specific sampling rates.




The GoldenSound Discord channel has an excellent explanation of all 21 input choices with recommended settings to get you started. The filter you like this week may be different than next week. But you do have to read the manual, which is included in the HQPlayer download.


I use HQPlayer with JRiver running in the background. I have used JRiver for years and it functions as HQPlayer’s pretty face. I discovered albums and individual songs can be dragged and dropped into HQPlayer. An internet search will come up with a couple of scripts to configure JRiver to play directly but I couldn’t get them to work, one has a typo that even when fixed doesn’t work and the other is too convoluted. I like having the ability to play music with either JRiver or HQPlayer. HQPlayer doesn't play mp3 so it is easy to click X to stop it running and use JRiver.

The trick to using JRiver with HQPlayer is to install Power Toys (Windows) or any other “Always On Top” utility. Start HQPlayer first, press Win+Ctrl+T (Power Toys), then start JRiver. Size HQPlayer to fit in the lower left of JRiver. Then Drag and Drop album covers or individual songs into the HQPlayer box. Each album or song added will then play next.




I don’t use Roon, muso or Alchemy Desktop. Many setup questions will have answers somewhere in the 1025 page thread at Audiophile Style, that is where I found out to set the bit depth to 20 bits for the May. Different DACs will use different bit depths.
https://audiophilestyle.com/forums/topic/19715-hq-player/

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #3 on: 31 Jul 2022, 10:31 pm »
I recently built a new music server after my 10 year old Intel Atom music server died after a long illness. I picked the Intel i7-9700 processor for two reasons: extra power in case I ever wanted to play around with oversampling and the 9700 is on the approved Windows 11 list.
https://www.audiocircle.com/index.php?topic=177495.msg1867916#msg1867916

HQPlayer’s upsampling and dithering algorithms will tax even the most powerful processors. The i7-9700 does just fine but I was able to stall it out with the wrong combo. Upsampling DSD64 to DSD512 had stutters. 44.1 PCM to DSD256 looked like it would take forever to process. Upsampling on the HAL MS-6 Music Server which uses the Intel Atom quad core processor would be an interesting challenge.


I took screen shots of different oversampling configurations using the free Core Temp app
https://www.alcpu.com/CoreTemp/

Intel i7-9700 idle load and temperature



HQPlayer 44.1 kHz upsampled to 384 kHz



HQPlayer 44.1 kHz PCM upsampled to DSD256



HQPlayer DSD64 upsampled to DSD512



The combination of the HoloAudio May KTE with HQPlayer just sounds right. The electronics get out of the way and all that is left is the music.

Highly Recommended.
« Last Edit: 31 Jul 2022, 11:43 pm by WGH »

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #4 on: 1 Aug 2022, 10:10 pm »
I was looking for a new challenge. I don't think I will ever emerge from this HQPlayer rabbit hole  :thumb:


The HoloAudio May thread in Audiophile Style also talks about HQPlayer, filters, and other DACs. Luckily only 104 pages.
https://audiophilestyle.com/forums/topic/58090-holo-audio-may-dac/#comments


Audiophile Style's old name was "Computer Audiophile" when Jussi Laako, HQPlayer's developer, posted a description of the filters that is more detailed than what is in the manual. Due to the fluid nature of web, old information can be hard to find or disappear completely.

Jussi Laako's filter descriptions are so important to HQPlayer's setup that instead of posting a link1, which I usually do, I did a copy and paste. I'm going to print this out for a handy reference too.


HQPlayer Explanation by Jussi Laako - HQPlayer Developer

First a bit explanation on time and frequency domain, please excuse me for some technical jargon. Frequency is signal change as function of time. Thus a signal has presentation in both frequency and time domains. "Linear phase filter" is a filter where all frequencies pass with same time delay. "Minimum phase filter" is a filter where all frequencies pass through as fast as possible, higher frequencies faster than lower ones. Longer/steeper filters change faster from passing frequencies to not passing frequencies as function of frequency. Shorter/gentler filters transition more slowly or "gently" from pass to stop as function of frequency. More accurately the filter wants to detect frequencies and transition pass/stop faster, longer time the filter has to "look" at the signal. This has side effect called "ringing" or rather "time blur". On the other hand, extremely short filter like a one that looks only at single moment cannot filter anything at all, because it sees only single point of time at once without any history or future (so it cannot detect any frequencies as those are a change over time). Linear phase filter takes equal amount of history and future into account during calculation. The problem in this is that it is kind of unnatural for something that is going to happen in future to affect already the present. Minimum phase filter on the other hand considers only from present to past, so it doesn't reflect things that are coming in future. This "ringing" is already in most RedBook recordings, since in most cases the ADC has gone through down-conversion and possibly another round at mastering from 24/96 or similar to RedBook. "Apodizing" filter is one that replaces or modifies this original ringing with it's own - that can be less than the original. All the filters explained below are more or less "apodizing" unless otherwise noted.

Why is "filtering" needed? Because otherwise upsampling/oversampling produces alias (distortion) components in frequencies above the original one. In down-conversion case it is even worse, because those components are produces below the original ones. D-A conversion also produces these components above half of the sampling rate frequency, and those are then removed by the analog reconstruction filters. Higher the sampling rate seen by the D-A conversion stage, simpler the following analog filter can be. Digital filters can easily outperform analog ones. Removing those spurious frequencies by filtering is called signal "reconstruction".

SET Up
So if I go from left to right on the main window...

First is the filter selection, most of these can perform either up or down conversion, depending on what is needed.
- So "IIR" the first one is how a steep analog filter would sound like, I don't recommend using it for anything else than upsampling and only at 2x or 3x ratios, although it can do higher ratios or down-conversion too. I think this is mostly useful to hear how "extreme analog" would sound like. Some DAC chips have slightly similar output stages.
- Then there are three types of traditional "FIR", these are similar in construction to those ones used inside most DACs, the "asym" one being somewhere between linear and minimum phases, only taking "near future" into account. So a traditional design made as good as possible.
- "FFT" is a special kind in that it performs it's work in frequency domain and is also fairly steep. This is technically closer to how audio codecs work than how upsampling is traditionally done. I don't know if any hardware oversampling implementation would use similar technique.
- "poly-sinc-*" these are the ones I use most and recommend the most, these can perform conversion from most input rates to outputs rates in a single pass and with a very low CPU load. Single pass approach maximizes the filter precision. (those who will eventually ask, these are synchronous converters)
- "sinc" is a true asynchronous converter and can perform conversion practically from any rate to any other rate. Although it is quite high quality, it has fairly high CPU load too and not recommended unless the "poly-sinc-*" ones cannot do the needed conversion.
- "polynomial*" is not a filter as such, but just polynomial interpolation approach to upsampling. These look only at small number of samples to calculate a new one and thus don't "ring", but on the other hand the filtering performance is poor too. These kind of filters typically also cause premature treble roll-off (roughly 3 dB or so at 20 kHz for RedBook material, starting from ~10 kHz). These are the controversial upsampling "filters" some people like a lot while others don't like at all. (non-apodizing)
- "minringFIR" this is a single-pass filter that is very similar to the polynomial interpolators above in that it is really short and looks only at very brief period of time, while still performing better at filtering and not having such treble roll-off issues. Not recommended for other than 2x/4x/8x/etc ratios. (non-apodizing)

Update on some recent changes regarding (Version) 2.9.1 and later:

There are now "poly-*-hb" filters for both up/down-sampling and DSD->PCM conversion. These are steep so called "half band" linear phase non-apodizing filters. These are in many upsampling cases completely reversible interpolation. Not really recommended for general purpose use, but interesting to play with.

The "poly-*" DSD->PCM converters (in DSDIFF/DSF Settings) have been heavily optimized and are now much faster while also having even more accuracy, so these are now actually one of the lowest CPU load while having best quality, most recommended choice now for the conversion.

Then to the next item, dither and noise-shaping. This is needed whenever any processing is performed. Reason is that calculations can lead to results that have more precision than can be expressed in the resolution supported by the DAC. Just truncating or rounding the result to fit the DACs precision causes distortion that is directly related to the signal. Dither hides this rounding error into very low-level non-audible constant noise (a bit like thermal noise) - then it's no more related to the signal. Noise-shaping takes this further by moving this noise to less- or non-audible frequencies. Especially multi-bit converters but to some extent others too also benefit from noise-shaped upsampling in improved linearity.

I don't recommend any noise-shaper for 44.1/48 kHz output rates, because there is no proper frequency space available where to park the noise.

There are number of noise shapers:
- "NS1" is a first-order shaper, just tilting the noise floor so that it increases towards higher frequencies and it has a bit of extra "against-the-wall" high frequency noise too. Not really recommended for anything, but included for completeness sake.
- "NS4" is fourth order shaper that has a gentle step to move a bit of lower frequency noise to ultrasonic frequencies. The only shaper that I would say is useful at 88.2/96 kHz rates.
- "NS5" is fifth order shaper that has been designed to be used at 352.8/384 kHz output rates or above. This one moves aggressively roughly 40 dB worth of noise from low frequencies to ultrasonic range.
- "NS9" is ninth order shaper variant for use with 176.4/192 kHz, the step from low to higher noise is more clear, but otherwise similar to the "NS5"
- "RPDF" this is just plain white noise, not really recommended, but also included for completeness sake.
- "TPDF" is industry standard flat triangular dither, good for any case, especially for 44.1/48 playback cases. Doesn't generate practically any CPU load either.
- "Gauss1" is Gaussian noise dither, should be more "perfect" than TPDF, but also loads the CPU more. Works for all cases too.

Third selection is set of available output sampling rates, computed based on what the hardware and selected filter are capable of, in combination.

Generally, I recommend choosing between "poly-sinc-*" filters and using highest possible sampling rate. Dither or noise-shaper chosen based on above description, "NS9" for 192 kHz output, "NS5" for 384 kHz output and "TPDF" or "Gauss1" for any lower rates...

To be continued, I'll make two other posts. One for the DSD->PCM conversion and maybe other one for PCM->SDM (DSD) conversion.

Hope this helps...


In most cases, poly-sinc family is a good starting point. Apart from poly-sinc-hb, all the poly-sinc filters are apodizing and can thus deal with the ringing introduced by typical decimation filters during the production phase of the recording, giving more consistent recording-to-recording performance.
Minimum-phase variants are usually good for multi-tracked studio pop/rock recordings that have lot of fast transients like drums/percussions. While linear-phase variants are usually good for classical music or other content recorded in natural acoustics with minimal micing techniques.
You can also try closed-form filter which is quite special, and non-apodizing by definition. In some ways similar to poly-sinc-hb. As a result it may sound good on good recordings while not improving not-so-good ones so much.

Closed-form, by definition is not apodizing, so it may sound good with good source material where the digital filters used for recording and/or mastering stage are sonically good. But it cannot fix the defects of bad digital filters from the earlier stages unlike apodizing filters do.

So apodizing filters like poly-sinc (except poly-sinc-hb which is non-apodizing) usually give more consistent performance regardless of source material. Because you hear only differences in the actual source signal when material changes, but not the differences between digital filters used in the source material production phase (recording/mastering).

I would put things roughly this way for filters:
- Minimum-phase filters for studio productions of non-classical music
- Linear-phase filters for classical and other music recorded in real acoustics with minimal miking.

OK, then a bit about configuration of DSDIFF/DSF (DSD) content conversion to PCM... 2.8 MHz DSD64 content is converted to 176.4 kHz PCM and 5.6 MHz DSD128 content to 352.8 kHz PCM. These intermediate formats can be further converted to any other supported output rate using methods outlines in my earlier post.

In DSDIFF/DSF Settings -dialog there are two selections, conversion type and noise filter.

Conversion type, this defines how the delta-sigma modulation is converted to lower rate PCM format:
- "normal" is a traditional multi-stage way to do the conversion, this is very similar to how modern delta-sigma ADC chips do the conversion to PCM output
- "single-steep" is a single-pass brickwall-conversion, this has technically very accurate results.
- "single-short" is a single-pass more gentler conversion, introduces much less ringing than "steep". I'm using mostly this one when I need conversion.
- "poly-*" these are similar to the "poly-sinc-*" ones mentioned in my earlier post, performed in single pass, but requiring really powerful CPU...

Noise filter, this is used to reduce the ultrasonic high frequency noise of delta-sigma modulation:
- "standard" this is the SACD/Scarletbook standard one. Recommended for most cases.
- "low" this has lower transition corner than the standard one, useful for equipment that is sensitive to the ultrasonic noise of delta-sigma modulation. Good alternative for the standard one.
- "slow-*" linear- and minimum- phase gentle noise filters. A bit more aggressive noise filter than above.
- "fast-*" linear- and minimum- phase steep noise filters. The most aggressive noise filter of these.

Then there's the "6 dB gain" setting, since DSD is specified to have max -6 dB of the theoretical maximum level in use, the content may sound quiet compared to PCM after the PCM conversion. This setting enables 6 dB gain to match maximum specified DSD level to maximum possible PCM level. However, this should be used only for content that doesn't exceed the specified maximum. There seems to be also content out there that exceeds this maximum level and would thus result in overload. Whether this leads to limiting actually depends on the HQPlayer's volume setting...

In the same dialog there are two settings related to native DSD playback.
- When "DirectSDM" is enabled, the internal delta-sigma processing engine for DSD content is bypassed. The engine is now capable of all the same functionality as is offered for PCM, including volume control, delay and convolution engine for digital room correction. But since DSD is about "Direct Stream Digital" (or probably originally Direct Sigma Delta before marketing department jumped on technical jargon), a direct path setting is provided.
- "Direct playback type" is selection to output different kinds of DSD-over-PCM packing methods supported by some playback gear in order to play native DSD. These days, the equipment is almost always "DoP marker" compatible, unless there is a native ASIO DSD driver (in which case "Native / none" is enough).

Then to the last and short post so far..

Regarding SDM (1-bit delta-sigma, or DSD in other words) output modes. So the player can perform all kinds of processing for PCM -> PCM, DSD -> PCM, PCM -> DSD and obviously DSD -> DSD.

When SDM output mode is selected in the main window, filter selection changes to control "oversampling" modes, matching descriptions of the earlier post. And dither selection switches to control the choice of actual delta-sigma modulator. Output sampling rate selector just shows SDM rates in MHz range, instead of PCM rates in kHz range.

There is also possibility to perform conversions like 192 kHz PCM to 2.8 MHz DSD. Or 2.8 MHz DSD to 5.6 MHz DSD (or vice versa). When processing is performed from DSD input to DSD output, all processing is performed at native rate, not at any low-speed PCM. The DSD -> PCM conversion now applies only when PCM output mode is selected and file being played back is DSD...

Important note! When performing any processing to DSD output, do not try to push the volume to max, use something reasonable like -3 dB setting max . DSD works better when it's not pushed to the max.


Comment from Jussi regarding NAA

Q- One thing that I'm curious about is the potential for high CPU and ram activity when using a tool such as HQPlayer to process the audio stream introducing electrical noise into the stream. How does it reconcile with the views of those (with and without commercial interests) that insist the computer should in effect run in limp mode with all non-essentials turned off, real time kernels etc?
A- That effect largely depends on the DAC how well it is isolated and how the computer itself is implemented. One can also use various USB isolator products (iFi, AudioQuest, UpTone). But there is a solution to address precisely that and it is called Network Audio Adapter or NAA for short. That is a small software module with asynchronous FIFO buffer between HQPlayer and DAC. Copper ethernet is transformer-isolated by the specification and for maximum isolation one can utilize optical ethernet. It also allows running HQPlayer server in a different room than where NAA + DAC is used. (combine that with Roon remote control and you have a great distributed system!)
NAA can run on a low-power PC (Atom or similar CPU) with Linux (preferable) or Windows, or some Mac computer. But going further it can run on various small very low-power ARM devices, like CuBox-i, BeagleBone Black or Raspberry Pi (or many many other similar ones). Usually these run very stripped down Linux with only the NAA service running and can be powered from high quality linear power supply.


1 tweak audio link

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #5 on: 2 Aug 2022, 12:20 am »
I always try to find the source of information, both ted_b and GoldenSound recommend setting the HQPlayer DAC bits (#5 in settings menu) to 20. But why?

Stereophile's John Atkinson measured the May, there is a  linearity graph in the article but I didn't know what it meant, now I do.


Fig.11 HoloAudio May, left channel, 1kHz output level vs data level in dBFS (blue, 20dB/vertical div.); linearity error (red, 0.1dB/small vertical div.).


A question was posted on Audiophile Style:
"I thought the May was capable of running 24 and 32 bit. Why not use the full bit resolution?"

Miska replied:

"Because it is not physically possible to create R2R ladder that is accurate to such resolutions especially at sampling rates suitable for audio. For this reason you get more accuracy by using less bits, but higher sampling rate.

"Here is for example Stereophile's linearity measurement of May...
"You can see it begins to go off at -120 dB which equals to 20 bit...
"But since 20 bits can give over 160 dB digital dynamic range over 100 kHz bandwidth, it is safe to use it, or even much less bits and still be sure that the noise floor is dominated by analog noise.
...But I'd say it is safest to use at most 20 bits, since there's no reason to use more and it is around the figure there is most consensus about in measurements."


poseidonsvoice

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #6 on: 3 Aug 2022, 12:24 pm »
Preach it WGH!  :thumb:









Here are the ingredients of my build:

  • Corsair iCUE 5000X tempered smoked glass case w/ front RGB fans
  • ASUS Prime Z690 motherboard (accepts Intel 12th generation processors)
  • Corsair RM850x power supply
  • Intel Core i9-12900K 16 core processor (up to 5.2GHZ)
  • Gigabyte GeoForce RTX 3080 Graphics processor (GPU)
  • 2 SSD’s, a small 250GB for Roon Core/HQP and larger 2TB for music, both are M.2 NVMe super fast drives clipped directly on the motherboard
  • Corsair iCUE H115 Elite Capellix Liquid CPU cooler for the main CPU
  • 32GB SDRAM from G.Skill Trident
  • Corsair iCUE SP120 rear exhaust fan

Special thanks to member Sledwards for helping me put together my 1st music server.

Inspiration for the build also came from Chris Connaker’s CAPS series of articles:

https://audiophilestyle.com/ca/bits-and-bytes/caps-twenty-part-one-r920/
https://audiophilestyle.com/ca/bits-and-bytes/caps-twenty-part-two-r925/

Part 2 explains the build of a server. Part 1 is for the streamer which I didn’t implement since I already have a good streamer.

So, like you, Roon serves as the pretty face, library cataloging software while HQPlayer does all the heavy DSP number crunching. I don’t use an analog volume control anymore. My last analog VC was a super tricked out Bent Audio TAPX using (4) Silver autoformers ($$$). Now I use the internal VC on HQPlayer, running it at DSD256 or DSD512 and since I wanted something tactile I could touch next to me, I use a Microsoft Surface Dial which communicates with Roon via a RaspberryPiW (Bluetooth then WI-FI). RooExtend software runs inside the RaspberryPiW.





Works great! It’s important to get your gain structures right in a system like this. My main speakers are 96dB sensitive and the Holo May (in DSD mode), only puts out ~ 2.8V RMS. With this setup a bare minimum of a 20dB gain amplifier (for the mains) is required since 3dB is already chewed up by HQPlayer as you stated above. But the signal/noise ratio is maximized and detailing is superb.

So in summary:

Signal flow: Custom I9 server (Roon core & HQP) w/Sonore Signature Optical Rendu SE v.2 using NAA w/Holo Audio May R2R dac (KTE edition) via Hapa Audio AerØ USB; BJC CAT6A ethernet cables for communication between router and I9 server. iPad Pro used for headless control and Microsoft Surface Dial used for haptic/tactile ’sensation’ of volume control, mute, advancement & reversal of tracks. Future experiments with Acourate/AudioLense pending with Mitch B since convolution filters can be easily implemented given the prowess of the server.

Best,
Anand.


« Last Edit: 21 Aug 2022, 12:36 pm by poseidonsvoice »

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #7 on: 3 Aug 2022, 04:29 pm »
I was beginning to wonder if I was the only person on AC using HQPlayer.
Very nice build Anand. I have been building my own computers since the stone age when the Cyrix processors were popular. I opted for a fanless design because my server is in a small living room so no updampled DSD512 for me.

The NVIDIA GeForce RTX 3080 graphics processor seems to be the preferred choice to do DSD512 using ASDM5ECv2, are you converting PCM to DSD?

Miska wrote:
"Regular original poly-sinc filters can take a very long time to initialize for single-stage versions to high conversion ratios. Especially between rate families. poly-sinc-long takes the most, for 44.1k to 48k x512 it can take days... "
https://audiophilestyle.com/forums/topic/19715-hq-player/page/1020/#comment-1204560



I'm not even close to being an HQPlayer expert but with the long Tucson summer of endless 100 degree days I have plenty of time to read.

Yesterday was learning about Apodizing filters day and how they reduce noise and distortion from 44.1 kHz mixes. A Mullard CV4024/12AT7 tube in my preamp recently got microphonic so I had to put the JJ 12AT7's back in. Not my favorite tube. A switch to the poly-sinc-short-mp minimum phase filter really helps tame the JJ's aggressiveness.

Audiophile Style has a wealth of information but it is buried in 1000's of posts. I use two methods to sort the wheat from the chaff:

1) I search by name. Miska is HQPlayer's the developer. I "Search posts by..." Miska to discover how HQPlayer works. ted_b is also very knowledgeable so I read his posts too.

2) A Google search can drill down even deeper. Adding "site:" after your search term uncovers gems otherwise missed. Here is one for ASDM5ECv2:
    ASDM5ECv2 site:https://audiophilestyle.com/forums/topic/19715-hq-player/page/

I like the ted_b post about Humble Pie as he learns about DSD upsampling.
https://audiophilestyle.com/forums/topic/19715-hq-player/page/365/#comment-658648
     

poseidonsvoice

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #8 on: 4 Aug 2022, 09:57 am »
I was beginning to wonder if I was the only person on AC using HQPlayer.
Very nice build Anand. I have been building my own computers since the stone age when the Cyrix processors were popular. I opted for a fanless design because my server is in a small living room so no updampled DSD512 for me.

The NVIDIA GeForce RTX 3080 graphics processor seems to be the preferred choice to do DSD512 using ASDM5ECv2, are you converting PCM to DSD?
   

Thanks for sharing the fruits of your knowledge and search engine tidbits. Every file in my server or from Tidal/Qobuz is upsampled to DSD, regardless of format. With Windows 11, DSD 256 is highly stable and DSD 512 is mostly stable. My colleagues who have the same configuration running on a Linux platform seem to have less glitches on DSD 512. So I may switch to Linux in the near future.

The plethora of filters to try is fun but it’s also fun to just sit back and relax without endless tweaking and a volume control (Microsoft Surface Dial, etc…) right at your fingertips.

My server is in a separate equipment room so fan noise isn’t an issue. And even though each individual fan is super quiet, once you have ten of them running and you are asking the server to output DSD 256 or 512, you will hear some fan noise but it’s still quite quiet imho.

I don’t really know how many fellas on AC understand how much digital has advanced to be honest. Many I feel are still in the stone ages, chasing disc spinners and such. Maybe there are those that just don’t share. For me, Audiophilestyle has been the best source of info for this type of project. I also firmly feel (having invested as much as $10K-$15K on a vinyl setup), that vinyl is nowhere close to digital and there are too many avenues for errors. My last setup was firmly beaten by an Auralic Vega dac and standard issue streamer and that was eons ago. After that, I decided that vinyl should be a lifestyle system for nostalgic purposes. So I setup a simple system in the family/breakfast room for all to enjoy without worrying about acoustics, imaging/staging/etc…only tonality.

Best,
Anand.

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #9 on: 4 Aug 2022, 09:09 pm »
With Windows 11, DSD 256 is highly stable and DSD 512 is mostly stable. My colleagues who have the same configuration running on a Linux platform seem to have less glitches on DSD 512. So I may switch to Linux in the near future.

I don’t really know how many fellas on AC understand how much digital has advanced to be honest. Many I feel are still in the stone ages, chasing disc spinners and such.

This thread will probably scare away anyone still using a CD player. As we get older, so do the CD players and people are always surprised to find out how expensive new audiophile quality CD players can be. A music server is about the same price with much better sound, by leaps and bounds, than an equally priced player. Add a DAC to a server and it's not a fair comparison at all. Yes, a DAC can be used with a player too but sound is still 44.1 kHz (no hi-res) and limited to whatever cheap parts are inside the expensive player. I used a CD player until 10 years ago, even though I upgraded preamps, amps, and cables the sound quality of my system was always limited by how much I could spend on a CD player, which was $400. A music server revealed how much music the CD players left behind on the silver disks.

The filters are fun to get to know, there are subtle differences and each are enjoyable. The change in sound is about the same as changing cables, power cords or even amps only cheaper because it costs nothing. Last week the stars aligned, the filter and music selection was perfect and I thought "this is what a $20,000 amp sounds like" because the server, Holo May, preamp and cables disappeared and all that was left was the amp and speakers with music floating in between. And my AVA Vision Set 400 amp was only $2000, yes they are that good. I never got that high level of sound using a CD player, which made music sound good but with no surprises.


My Intel i7-9700 fanless music server (no NVIDIA card) does have it's limits. HQPlayer's extreme hi-res upsampling will require an extreme computer like Anand's build with a NVIDIA card1 if you want to try glitch free 44.1 to DSD512 upsampling. Staying within PCM and going from 44.1 to 352.8/384 is very worthwhile and musically satisfying. A Intel Atom based music server may be able to do it because the processor load is so low. A lot more listening will be needed to see if DSD sounds better than PCM or just different.

The Intel i7-9700 can upsample 44.1 kHz to DSD256 glitch free with the right modulator. The ASDM5 adaptive fifth order one-bit delta sigma modulator works. The slightly more accurate ASDM5EC is more processor intensive and has drop outs. The DSD256 upsampling is right at the limit of i7-9700 and a fanless case.

CoreTemp readings after an hour of upsampling 44.1 kHz to DSD256 was right at the edge but stable with core temperatures bouncing to 99° C. The cases side heat sink fins were very hot to touch. Power hit momentary peaks of 64W before dropping. The Streacom FC10 case is rated for a 65W. The Intel Core i9-12900K used by Anand is between 125W-241W and would melt in a fanless case.




1  On 5/28/2020 Miska wrote:
Note about the new sinc-L filter (in HQPlayer Desktop 4.6.0); to use this one especially to higher DSD rates you'll likely need a GPU. To DSD256 it requires about 8.3 GB of GPU RAM, so my RTX2080 runs out of memory and thus doesn't play. However, on RTX2080Ti plays fine to DSD256 with a bit over 10% GPU load. For DSD512 (not tested) you'll likely need TITAN RTX with it's 24 GB of RAM should be enough for the ~16 GB needed.



Freo-1

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #10 on: 25 Sep 2022, 03:37 pm »
Enjoyed reading this thread.  No doubt digital has made many advances. 


Since I still have a lot of optical media,   would still desire a setup to use the media,  along with streaming. What works for me is using a optical transport to a Chord M-Scaler.  The M-Scaler does an outstanding job of cleaning up and maximizing the digital sources.  The sound from this front end has to me been as good as any server/streaming setup I've come across to date.


Certainly,  for many, the streaming/server setup makes a ton of sense.  I use it for convenience,  but still find I can get compreable performance from optical via the Chord M-Scaler.

mresseguie

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #11 on: 26 Sep 2022, 12:42 am »
A big thank you to both Wayne and Anand for chatting about your experiences with the Holo May KTE DAC, HQPlayer, etc.

Just 24 hours ago, I <finally > quit waffling  :roll: over which DAC to try next, and ordered a spanking new Holo Spring 3 KTE w/volume control. Ostensibly, this will be placed in a secondary system in which a single box DAC powering a SS amp is desirable. [Of course, I’ll try the Spring in my main system with and without my D Sachs preamp.] I do not have HQPlayer, Roon, nor JRiver. [I’m still in the stone age.] I use aging iOS computers to play music from SSDs, discs on my CDT, and stream Tidal.

May I pick your brains with a few basic questions?

My iOS computers are ~8 to 10 years old. Can I achieve anything DSD256 with them, or is it time to purchase a new very powerful computer? Is the currently most powerful MacBook Pro with 32Gbs of RAM powerful enough? What about the fastest Mac Mini?

I have two SSDs of SACD files. Can I play them to a satisfying level using the Spring without using any of the above mentioned software? [My NOS DAC is unable to play them.]

Can I begin using HQPLAYER without also adding Roon?

I thank you in advance for any assistance you can offer.

Michael

JackD

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #12 on: 26 Sep 2022, 12:48 am »
Congrats on the new DAC Michael.  I think you'll really enjoy it as I do mine.  No preamp module in mine as I leave that to the Supratek or Sachs preamps.  As long as you have a control point (streamer or laptop) to que the files on the two SSD's you should have no problem playing them with the Spring 3. Unless you just want to explore Roon, HQ Player or both where much more computing power will be needed a simpler solution and much cheaper might be to buy an iFi Zen Stream from either MD or Crutchfield who both have 60 day return policies and connect the SSD to it.  You should be able to play them either using the iFi app or the $5.99 mConnect app.  You can also use Tidal Connect.  If it doesn't work out for you send it back and if it does add an LPS and keep it.

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #13 on: 26 Sep 2022, 01:49 am »
May I pick your brains with a few basic questions?

My iOS computers are ~8 to 10 years old. Can I achieve anything DSD256 with them, or is it time to purchase a new very powerful computer? Is the currently most powerful MacBook Pro with 32Gbs of RAM powerful enough? What about the fastest Mac Mini?

I have two SSDs of SACD files. Can I play them to a satisfying level using the Spring without using any of the above mentioned software? [My NOS DAC is unable to play them.]

Can I begin using HQPLAYER without also adding Roon?

I'm not a Mac guy so unfamiliar with what is available for music players. HQPlayer is a stand-alone player, no Roon or streaming service required. I no longer have Tidal and never used Roon. I prefer to listen to flac and DSD.

No need to get a new computer until the old one fails. My old server with an Intel Atom processor worked fine for basic music playing using JRiver. So far it looks like Anand and I are the only two people on AC that use HQPlayer, it does have a free trial, you would want the Desktop version. HQPlayer is not cheap and it is complicated to learn but the benefits far out class any other players I have tried including JRiver, Audirvana and Foobar2000. I only started upsampling when I built a Intel i7-9700 based server.

DSD64 (SACD rips) will play perfectly into the Holo DAC. JRiver's default setting converts DSD to PCM, checking a Bitstream DSD box enables pass-through. HQPlayer has DSD pass-through too or upsample DSD to whatever your computer can handle. Don't know if other software has this feature.

If you try HQPlayer with upsampling and the music stutters or the laptop fan sounds like a helicopter (which it will) then a more powerful computer will be needed. I think a laptop will always be too noisy playing hi-res. HQPlayer is professional software that has been adapted for hobbyists. A powerful computer works best.

Most people would opt for the free Foobar for Mac
https://www.foobar2000.org/mac


pis99

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #14 on: 26 Sep 2022, 04:12 am »
Maybe you can start trying out Hqplayer on your aged Mac with only PCM upsampling to 1.536 Mhz. With LN15 dither filter, you still can hear the nice portion of Spring 3 in NOS mode with Hqplayer. I have both Spring and May and I am from Taiwan.


A big thank you to both Wayne and Anand for chatting about your experiences with the Holo May KTE DAC, HQPlayer, etc.

Just 24 hours ago, I <finally > quit waffling  :roll: over which DAC to try next, and ordered a spanking new Holo Spring 3 KTE w/volume control. Ostensibly, this will be placed in a secondary system in which a single box DAC powering a SS amp is desirable. [Of course, I’ll try the Spring in my main system with and without my D Sachs preamp.] I do not have HQPlayer, Roon, nor JRiver. [I’m still in the stone age.] I use aging iOS computers to play music from SSDs, discs on my CDT, and stream Tidal.

May I pick your brains with a few basic questions?

My iOS computers are ~8 to 10 years old. Can I achieve anything DSD256 with them, or is it time to purchase a new very powerful computer? Is the currently most powerful MacBook Pro with 32Gbs of RAM powerful enough? What about the fastest Mac Mini?

I have two SSDs of SACD files. Can I play them to a satisfying level using the Spring without using any of the above mentioned software? [My NOS DAC is unable to play them.]

Can I begin using HQPLAYER without also adding Roon?

I thank you in advance for any assistance you can offer.

Michael

WGH

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #15 on: 26 Sep 2022, 05:51 am »
I wouldn't bother using HQPlayer or thinking about upsampling for the first month. Pick a music player and listen for 100 hours, once you get to know the sound of a NOS DAC then you can decide if you want to play around. The effects of HQPlayer's different filters and samplers are subtle and you need a point of reference otherwise you are throwing darts in the dark not even knowing where the target is.

Finding the right boxes to check in your music player software to get DSD pass-through will be your first challenge, that way you can hear DSD64. The front display will let you know when you got it right:



An old thread in AudiophileStyle says:
"Core audio in Mac is limited to DSD128 and only custom drivers bypassing Core Audio can do 256"
https://audiophilestyle.com/forums/topic/28637-holo-audio-spring-dac-r2r-dsd512/page/4/

But this is from 2016, a month will give you time to research and find out what resolutions a Mac can do. I didn't see any Mac drivers on the Kitsume site. The Windows drivers unleashes the full potential of the Holo DAC and must be installed.

brj

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #16 on: 26 Sep 2022, 06:41 am »
My iOS computers are ~8 to 10 years old. Can I achieve anything DSD256 with them, or is it time to purchase a new very powerful computer? Is the currently most powerful MacBook Pro with 32Gbs of RAM powerful enough? What about the fastest Mac Mini?

I have two SSDs of SACD files. Can I play them to a satisfying level using the Spring without using any of the above mentioned software? [My NOS DAC is unable to play them.]

Can I begin using HQPLAYER without also adding Roon?

Assuming you mean MacOS instead of iOS...

I run Roon and HQP on a 2012 Mac Mini (2.6 GHz i7 quad core w/ 16 GB RAM) without issue, though I can't run quite the same level of filters as Anand with his new beast of a machine!  :wink:

I'm able to run the -2s filters at the DSD128 bitrate with the ASDM7ECv2 modulator.  I should add that I'm also using HQP's convolution engine to implement the EQ for the drivers of my active speakers, as defined by the speaker's designer.  (I used REW to create the needed impulse response file.)   Not bad for a 10 year old machine!  I do plan to update my audio server in the not too distant future, however, as the PCIe bus finally seems to be getting a bit unstable and I do want to hit at least DSD256 with some more aggressive filters.

I guess I should note that I also have a Holo May, having upgraded from a Denafrips Terminator previously.  My music is stored on a Synology NAS, not the Mac Mini.

You can certainly use HQP by itself, though its user interface isn't nearly as impressive as its upscaling capabilities.  (I do use Roon as a front end to HQP, but I'm very much less than thrilled with their recent shift to requiring continuous internet access to play back local files.)

I know of several folks running HQP on Mac laptops, by the way, as the impressive memory bandwidth of the M series processors is well suited to HQP, especially as you move beyond the base M1 processor.  Jussi (HQP developer) has an M1 Max Macbook Pro, for example.  (Though he seems to have 1 of everything at this point!)  I prefer a dedicated machine, but a laptop is certainly an option if you want to consider it, especially if you plan to make use of an NAA.  The latest Mac laptops have more powerful processors than the current Mac Minis, up to an M1 Max, though the Minis are commonly expected to have updates announced next month.  That's still not going to do what a high end machine like Anand's will do, but it will go further than most people realize.

(Btw, I also route the optical audio output from my TV into my Apogee Element which sends it into the same Mac Mini over Thunderbolt.  I then use Rogue Amoeba's Loopback tool in combination with Apple's AU Lab to perform driver EQ on that stream, using the same impulse response file as deployed in HPQ.  I have scripts written that I trigger with a Flic smartbutton to toggle back and forth between the two configurations.  So my 2012 Mac Mini gets a workout!)

Short version - you have Mac options for HQP if you want them.

P.S.  By using an NAA, you bypass the Core Audio DSD128 limit that WGH mentioned above.  You can run as high a rate as the Mac you choose can process.

mresseguie

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #17 on: 26 Sep 2022, 07:06 am »
Oh, boy! This is great feedback.  :thumb: :thumb:

brj: You’re correct. It is MacOS. Thank you for pointing it out. The former English teacher in me tries to avoid making such mistakes.

I suspect I’d be remiss if I didn’t mention that I recently bought a Zidoo Neo @ server/streamer. It’s got an ESS9038 DAC chip. My original intention was to skip the internal DAC in favor of my NOS DAC, but it’s so easy to use the internal DAC (which sounds pretty good). I’m still learning how to use it, but I do know that it’s unable to process SACD files. [I didn’t buy it with SACD capability in mind.] At this point, I don’t know which system the Neo will end up being used with.

I’ve more I want to say, but no time to finish it now.


poseidonsvoice

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Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #18 on: 26 Sep 2022, 03:13 pm »
Good discussions, not much to add here.

brj, nice to see you back!:

For clarity, since the Holo Audio dac is a 2ch dac, is your active filter implementation occurring after the DAC, i.e. in the analog domain or is it in the digital domain? Perhaps that should be a thread for separate discussion since I imagine you have a very specific setup here.

My dream would be a dac the equivalent of the Holo Audio NOS but 8 ch instead of 2ch so I can implement something similar to jtwrace did with his M2's. The achilles heel here is the quality of the dac.

Of course my server will easily accommodate the individual channels of convolution filtering.

Best,
Anand.

brj

Re: HoloAudio May KTE DAC with HQPlayer Review
« Reply #19 on: 26 Sep 2022, 06:14 pm »
My program at work has had a slight delay, so I have the tiniest bit of breathing room for a week or two! :)

Anand is settting the hook for me, as we've talked this a bit in the past ( :wink: ), but I'll provide a brief response for the benefit of other interested parties.  I agree that if it goes much further, however, it should be broken out into a separate thread so as to avoid detracting from WGH's excellent review.

So... at the most basic level, it's important to remember that the crossover in a typical passive speaker is doing 2 things - splitting the full range signal between the various drivers (tweeter / mid / woofer / etc) and adjusting the signal sent to each driver to ensure that the driver responds as the designer desires (flatten any peaks in the response, avoid the breakup region, etc.)

My system simply separates those two functions and performs them at different points in the signal path.  I did this because I wanted a fully active system that still allows me to use standard 2 channel DACs.  The driver EQ is performed digitally on the Mac Mini before the DAC, and the frequency splitting happens to the analog signal before the amps.  (Thus making it an active system.)

The end-to-end connectivity to my speakers:

Mac Mini w/ Roon and HQ Player -> HQ Player NAA -> Holo Audio May DAC -> pre-amp -> Pass XVR1 analog line-level crossover -> 2x stereo amps -> 2-way Gedlee Abbey 12c(a) speakers

(My subwoofers are managed by a Xilica speaker management unit fed by the second output of my pre-amp, but that's not important here, except to note that the driver EQ required by my mains does not reach into subwoofer territory.)

I used REW to parametrically implement the exact full-range EQ adjustments as defined by Earl Geddes for my Abbeys, and then exported the corresponding impulse response as a 32-bit, 384 kHz WAV file.  These EQ adjustments are NOT implementing room correction - they merely correct the driver's output to achieve Earl's target response for both the compression driver and woofer.  We're just doing digitally, at very high resolution, what he does with resistors, caps, and inductors in the passive version of the speaker, but with none of the associated electrical losses or part-value matching challenges.  After HQP up-samples the incoming music signal per my specified filter and modulator settings, it then convolves the driver EQ impulse response file with the live, upsampled music stream, and thus the signal leaving the Mac Mini for the NAA has the driver EQ already implemented before it gets to the DAC.

After the pre-amp, the Pass XVR-1 splits the full range analog signal between tweeter and woofer (using the same slopes and corner frequencies defined by Earl).  That means that I now have 4 outputs from the XVR-1 to amplify, so I have one stereo amp driving the tweeter and woofer of the left speaker, and a second stereo amp driving the tweeter and woofer of the right speaker.

Between these digital and analog domain adjustments, I have almost unlimited flexibility without needing to go to multi-channel DACs.  (Given that my speakers didn't need more than the 24 dB/octave high-pass/low-pass filter capability of the XVR-1, at least.)  Plus, I can have HQP convolve additional impulse response files if I like, so I could have a second IR file that implements room correction if desired and third that implements the accoustic signature of any space for which I can find an impulse response WAV file.  Want that studio recorded a cappella group to sound like they are singing in a cathedral?  No problem!  :)

(The harder part is finding high quality, high resolution/bit-depth IR files capturing such acoustic spaces.)

Some [lightly edited] helpful comments from Jussi regarding various aspects of using convolution in HQP:
  • It is a good idea to use highest bit depth and sample rate available. If you store filters at 192 kHz, you can leave "HF Expand" option disabled in HQPlayer and the filter works fine for hi-res content too.
  • Selecting the "Normalize samples to peak value” option in REQWizard when making an impulse response filter changes the overall filter gain, but otherwise it has little effect as long as filters are saved as 32-bit.  It mostly matters if you use different EQ settings for different channels, for that case you may want to NOT use normalization. Otherwise the channels may end up having different overall level (channel balance goes out). When using just single filter for all channels it may help getting suitable gain.
  • If you have any positive gain EQ peaks, you may need to apply negative gain compensation in the HQPlayer convolution engine configuration dialog (at least if you normalize the peak) to compensate for the gain peaks, so that content already close to 0 dBFS is not driven into clipping/limiting. When you load an impulse response to HQPlayer, estimated filter gain is shown in the dialog.  Also keep eye on the "Limited" counter in main window while playing. It should stay at 0 and never increase from there.
  • When you switch the filter in/out in the main window while playing, and in case it has positive gain peaks, the overall volume level should sound about max peak gain amount lower than without filter.

Ok... not so brief!  :lol:

(And yes, with this setup and 30 very beefy class A watts driving each individual speaker driver, the dynamics of my system are note worthy! :) )

The only slight caveat is the SNR of the XVR-1 - it's staggeringly flexible and capable, but it's electrically noisier than the rest of the system, meaning that it's likely the source of the slight hiss that I hear when my ear is next to one of my compression drivers (but not at my listening position in my very quiet listening room).  It's also impedance balanced, rather than fully differential unlike the rest of my system.  Someday, I'd like to find someone to build a fully differential, discrete version of my line-level crossover, as I've found no reason to mess with the filter settings in a very long time.