[srb]

Sasha,
 
Not sure about the answer to that.  As was previously discussed, perhaps the EA Pace Car can accomplish the jitter reduction, but I have no first hand experience.
 
I think maybe the hardware I seek is not yet available, but hopefully will be in the near future.  I think there may be proprietary music servers which could accomplish this, but I would like to be able to control a piece of hardware with either a PC or MAC with my choice of playback software.
 
The piece of hardware I am hoping will appear is a box the size of a CD player, with space for 2 industry standard SATA drives, and an ethernet connection to the host computer.  Whether it will have a built-in DAC or be able to feed an external DAC with some form of master clocking, I don't know.
 
For now, I am getting some pretty good sound out of the S/PDIF output from the integrated Realtek chip in my Gigabyte motherboard fed to my external Stello DA100 DAC.
 
Is it the equivalent of your high-end CDP?  I doubt it.  But again, the versatility is important to me and I'm sure there will be more affordable hardware solutions in the near future.
 
Steve

[Sasha]

I do not think as well that such solution exists, all music servers I have come across are geared towards convenience and not top performance, meaning none match top CDPs.
Your HW description is something I am hoping for as well, well designed, with all the shortcomings of a computer environment taken care of. What is Bryston doing these days anyway? 

[Crimson]

Sasha,

Comparisons were quite simple when approaching it from the point of view that the transport/dac and Mac/dac combos were individual sources. Playing the same track on each source and then switching between the two made comparisons quite simple. Granted, I couldn't connect the Reimyo to the Mac or the Wavelength to the CEC, but when taken as a whole there was a clear preference of one source over the other.

[doctorcilantro]

Good thread. Interesting facts about Amarra and CoreAudio; I wasn't aware of that.

I think many developers and engineers (DACs) get frustrated or have been with Windows in the past, thus they have written off Windows as a capable platform. Things like asynchronous usb have been positive results of that frustration.

I blend my audiophile need with pragmatism and usability. I simply can't deal with thousands of CDs, and the benefits offered by the front ends on Windows truly outshine the Mac offerings. A decent sound card (even onboard) feeding an external DAC via ASIO (even wave, yes, wave now that K-mixer is gone) can yield stunning performance.

If you're feeding a good DAC, why is some pre-DAC jitter an issue? Of course, we should minmize it but I don't see this as a major obstacle.

CRIMSON - what are you trying accomplish that you can't with your current setup? Currently you can have a wired high-end PC source, and also stream (wireless) high-res lossless to another PC (web-book?) feeding another DAC/hi-fi....

I'm not sure what people use on the MAC (transporter? new airports support 96kHz?)

DC

[doctorcilantro]

I do not think as well that such solution exists, all music servers I have come across are geared towards convenience and not top performance, meaning none match top CDPs.
Your HW description is something I am hoping for as well, well designed, with all the shortcomings of a computer environment taken care of. What is Bryston doing these days anyway? 

Are we talking about serving audio over wireless (streaming), or wired PC audio solutions (akin to CDP). The jargon matters, I'm confused.

What's the main obstacle? Please be specific. Noisy PSU (find a linear PSU or use low-power system)?

Jitter laden output from PC (use a high quality external DAC)?

Physical noise in a listening room (build a silent ITX based PC)?

Sound card exposed to electrical noise ("a simple way to get a very low noise floor is to use an external sound card, although not all of them feature galvanic isolation thus leading to ground loops. This may be solved by taking advantage of digital optical outputs or coaxial outputs with transformer coupling" - diyaudio)?

DC

[Crimson]

CRIMSON - what are you trying accomplish that you can't with your current setup? Currently you can have a wired high-end PC source, and also stream (wireless) high-res lossless to another PC (web-book?) feeding another DAC/hi-fi....

I'm quite content, and curious as to what gave you an impression otherwise. My Mac feeds my main system via USB and fire wire, as well as via wifi to other 'lesser' systems in my household, and all is controlled via a single device: my iPhone.

[doctorcilantro]

Sorry I guess I meant SRB, not you CRIMSON - sounds like your enjoying your setup.

I too control my systems (three zones) with J. River using my iPhone (or Gyration remote). Very handy and incredible smooth, made possible by RiverMote.

The thread I linked to above is really interesting.

"I'm not sure how that works though. A CPU operates at over 1GHz or so, so clock jitter usually will have some performance issues on the CPU and core process itself, far more so than on a 192KHz (at best) audio stream. But whatever I read and try and experience, it seems that a modern motherboard is a EMI disaster, and to convert a data stream to audio as far outside the PC as possible is the best way (so even the 'controller' to be externally located and galvanically isolated). Even my poor little Alien DAC is a demonstration of this, it is easily able to come close to the performance of the much more expensive Delta 66 in its stock form. so yes, I believe a power supply may have an effect. How much, and whether it will be audible I don't know."

It would suffice to say: get a decent system built (good psu, low power HTPC), use an external sound card (1616M even which has converters on the Microdock), push that to an external high quality DAC, enjoy your hi-fi (do this on a Mac or PC).

My last system a 3gHz quad-core for hi-fi and home theater, had a 1212M feeding a Benchmark, then Lavry, sounded great. Now I'm in mini-ITX territory. There are so many benefits to going discless; it's really an enjoyable endeavor to build a system and rip your discs whether you use a MAC or PC. I will say this, if you are a meta-data freak (i.e. love factoids, lyrics, names of players , studios, etc.) I think a PC would be more rewarding as ou can create your own meta-data fields and really reap the benefits of a database driven system like J. River.

The piece of hardware I am hoping will appear is a box the size of a CD player, with space for 2 industry standard SATA drives, and an ethernet connection to the host computer.  Whether it will have a built-in DAC or be able to feed an external DAC with some form of master clocking, I don't know.

What does the host computer do if the data is stored on the box with onboard DAC? Files should be centralized for tagging/access/playback imo. Are you talking about having a 2nd system linked into your main system? Sorry, I'm not very clear what you are trying to accomplish, a wired or wireless connection to a 2nd system. My lesser systems, as Crimson also alluded to, are Airport Express units, but if in need of a 2nd hi-fi over wireless: I stream lossless audio over WAN to my office hifi (PC>external DAC>tube headphone amp). I think the key is to just use any PC really (kill unneeded processes but that may be an old hat by now - configuring ASIO, etc.) and integrate it with good hi-fi gear. I plan on streaming in the same way to a laptop with optical out to our "Summer home" (grandma's house).

I think maybe the hardware I seek is not yet available, but hopefully will be in the near future.  I think there may be proprietary music servers which could accomplish this, but I would like to be able to control a piece of hardware with either a PC or MAC with my choice of playback software.

YES!

DC

[Sasha]

DC,

Pre-DAC jitter is an issue because there is no jitter immune DAC regardless of what manufacturers claim. Never was and never will be.
You have to address jitter at the source in order to have PC based transport approach the performance of best CDPs.
In regard to music servers, I am talking about any of them available.
For example, offerings from Squeezebox are pure junk, digital outputs are extremely jittery.
How such devices receive data (wireless or wired Ethernet) is irrelevant from the perspective of poor implementation, they all suck, although just for the argument?s sake I would never use wireless.
Or take McIntosh music server, extremely pricy for such mediocrity in performance.
The main obstacle is that they all output too much jitter, manufacturers would have to explain why, could be due to poor design, PSU, ground issues, I do not know and I do not care, the point is that digital signal is too jittery.
And I do not want to get engaged into pointless discussion how someone is using Transporter or whatever and is extremely satisfied.
It may sound great to you.
My argument is that so far there is no such source that approaches top CDP performance.

[doctorcilantro]

Pre-DAC jitter is an issue

How big of an issue? How much jitter are we talking about here?

Wireless is an option. 1's and 0's to another computer, then to an external DAC; no Transporter or Squeezebox. Technically it's not streaming audio, just a source that happens to have a non-local origin.

CDP seem more at risk of jitter - you're doing on the fly optical reading and either internal DAC or sending via digital out to a DAC. What's so different about a high end CDP than a well executed CDP.

We can rip CDs with EAC, Accurate-Rip, Secure Modes etc. compare bit for bit to other rips, before buffered playback...does a high end CDP do that? Even EAC can let errors slip by, I doubt very much that a high end CDP can do better on the fly.

And no matter how much effort and money you put into it, PC (or MAC) based transports still do not match best optical players, this has been my experience and experience of many others who tried to take it to the extreme and achieve performance that would better optical transports. Not happening.

Care to elaborate? List general specs of the PC you or friends have tried? DACs? OS's? Lossles, un-encoded files? What players? foobar? J. River? Amarra? Tweaks? Compared to which CDPs?

I simply fail to believe given what I have heard that there is such a marked difference is fidelity although you may have heard more systems compared than I.

DC

[Sasha]

DC,

To give you an example of jitter figures, Squeezebox has around 380ps jitter on its SPDIF and around 800 on its TosLink. Far too much and very audible.
You can read in this thread how comparison was done and what HW I used. It was very methodological approach, not some ad-hoc listening with multiple variables in the play.
Well executed CDPs do not have optical reader electronics send digital signal with embedded clock to DAC, in fact no clock is sent at all. Clock is located next to DAC, source is slaved to it.
You are missing the point with story about ripping and EAC, the issue is jitter, not bit perfect reading.

[doctorcilantro]

Okay, I see. How does the Wadia extract information from the optical disc?

"Simaudio Moon Evolution Andromeda Reference CD player
$12,500, reviewed by Brian Damkroger in January 2008.
Playing CDs (the Simaudio also has a useful input for external data), the Andromeda offered low levels of word-clock jitter, at 286ps peak?peak."

This was listed as capable of full high-resolution playback section in the Stereophile tests. My 1616M does about 500ps at 44kHz. I wonder if that goes down when used at 96kHz? Then would you agree, there is some reduction by the DAC being fed?

Conclusion
There is no consensus about what levels of jitter in a digital product's output are acceptable?the audibility will depend on both level and spectrum. Some authorities also insist that the ear will tolerate relatively high levels of jitter, up to a few nanoseconds, though that has not been the experience of this magazine's writers. But as an indicator of a product's ultimate resolution, these measurements of jitter and noise floor are illuminating. The McIntosh, PrimaLuna, and Krell are all disappointing in different ways, while the Simaudio, Meridian, Bryston, Boulder, and Ayre measurements in particular indicate the presence of some serious audio engineering talent on the staffs of these companies.

http://www.stereophile.com/features/1208jitter/index3.html

Seems like up near 300ps was good enough for them; I guess you have really sharp ears.

Does Wadia list jitter specs? Do any CDP manufacturers?

DC

[Sasha]

You can read about Wadia?s clocklink on their site: http://www.wadia.com/technology/clocklink/
This approach is adopted by many top CDPs, not just Wadia.
This will help understand why PC/MAC does not sound as good.
What is needed is further reduction in jitter at the source, so that the jitter reduction methods DACs employ can bring it below the audible level.
And that reduction on PC/MAC or whatever Media Server can be achieved by addressing the shortcomings of computer environment.
It is all in design and execution.
Some parallels, poorly executed amplifier may have published and largely meaningless measurements like THD at 1kHz that are arguably below hearing threshold, yet it will not sound good at all when compared to another well executed amplifier with the same measurements (although closer look at measurements not limited at 1kHz may reveal reasons for poor sound).
Unless of course someone falls into the ?all amplifiers sound the same? camp, such person will argue till the end of the world that it is all the same.
Same with argument on VBR MP3 versa lossless.
Add on top of that the perception, for someone the difference in performance between best PC transport and CDP is not worth mentioning, or so minor that it does not outweigh the convenience of PC.

The conclusion you quoted clearly states that there is no consensus about audible threshold for jitter, and that it depends on both the level and the spectrum.
There are those that talk about jitter of few ns being acceptable, this just shows their ignorance.
Is Stereophile review for you an indication that 300ps is not audible?
They list players and measurements that are ?good enough? for hi-rez audio playback, nothing more.
How do you draw conclusions from their review that PC based transports match performance of top CDPs and that you need sharp ears to hear it?
You do not need sharp ears, just an opportunity to hear it.

[doctorcilantro]

I wonder if Gordon Rankin's Wavelength DACs would be jitter immune?

DC

[James Tanner]

Some might be interested in this:

http://www.aes.org/e-lib/browse.cfm?elib=8354

james

[doctorcilantro]

http://www.blacklionaudio.com/Products/Black+Lion+Audio+Micro+Clock+mk2

[Sasha]

External clocking does not address the root cause of the problem and does nothing to minimize jitter at the source.
In many cases it makes things worse, and certainly so when used with good CDPs.
Why would anyone want to clock DAC or players such as Wadia externally in a palyback channel?

[doctorcilantro]

I'm confused, I'll admit.

If I use the 1616M coax input and sync to an external word clock with 1ps of jitter, you're saying that won't help to reduce the jitter output?

You can sync to internal or external with many sound cards. I don't have a Wadia. I'm talking about syncing a sound card to a low jitter clock and then feeding an external DAC (peachtree Nova).

DC

[Sasha]

I'm confused, I'll admit.

If I use the 1616M coax input and sync to an external word clock with 1ps of jitter, you're saying that won't help to reduce the jitter output?

You can sync to internal or external with many sound cards. I don't have a Wadia. I'm talking about syncing a sound card to a low jitter clock and then feeding an external DAC (peachtree Nova).

DC

Because that great external clock has to be extracted from clock input of whatever device you are clocking, and by the time you get it extracted it is no longer such a precise clock.
Exactly the same problem you have with PLL, no matter how good implementation of PLL is you are screwed, that is why this whole premise of ?jitter immunity? does not work and that is why we have this discussion.
You do external clocking in different applications that have no bearing on playback, what we are interested in.
And it is not only the clock precision that impacts jitter. You can slap super precise clock right on the sound card plugged into PCI bus and powered from it from switching PC PSU. You accomplished nothing with it.
Sound card will output high jitter.

[doctorcilantro]

So you are saying the PC contaminates the digital output at the sound card? even with a high quality clock on card....

You do external clocking in different applications that have no bearing on playback, what we are interested in.

You mean if I clock my sound card to an external source, and then send digital out to a DAC. Just trying to clarify what you mean with regard to no bearing on playback.

The Wadia technique seemed akin to adding an external word clock to me; they seperate the two. Seemed as though their diagram indicated jitter creeping on the actual digital audio signal.

What would you like to see as an acceptable jitter measurement out of a sound card? Stereophile is listing 200-300 as acceptable for high-rez. How audible is going from 600>300>50ps on a highly resolving system?

DC

[Sasha]

So you are saying the PC contaminates the digital output at the sound card? even with a high quality clock on card....

You do external clocking in different applications that have no bearing on playback, what we are interested in.

You mean if I clock my sound card to an external source, and then send digital out to a DAC. Just trying to clarify what you mean with regard to no bearing on playback.

The Wadia technique seemed akin to adding an external word clock to me; they seperate the two. Seemed as though their diagram indicated jitter creeping on the actual digital audio signal.

DC

Yes, PC contaminates the digital output at the sound card, that is why I am talking about addressing jitter at the source.
I tested this as well, I moved the same sound card between PCs with different HW enabled and SW installed, and consequently with different OS footprint, there were clear differences, PC that I build specifically for playback purpose, the completely fanless one that that had all non-essential HW and SW disabled, had less negative impact on playback.

And no, by different application I mean multiple devices in a digital chain, something you would find in production. Not in playback where DA conversion occurs.