[craig in SD]

I'm shopping for an amp to set up in a new dedicated 2 channel system (my first dedicated 2 channel in a quiet space--hooray!) and I am really drawn to the notion of a direct digital amp/power DAC.

My source is a Squeezebox Touch. Speakers are Monitor Audio Silver 5i (small floorstand, 8 ohm, 89 dB sensitivity).

Conceptually, I like the "fewer components" approach embodied by a power DAC (I also like the notion of crossover-less full range speakers, FWIW, but don't own any) and after listening to an NAD C390DD amp last week I was really impressed, but it is still a bit above my budget. I did see a used one on Audiogon that I might be able to stretch for. What I really liked was the separation, detail, and soundstaging it created. Instruments were crisp and precisely placed in the soundstage.

I wonder: do products like the Nuforce DDA-100 or Wadia 152 Power DAC sound and measure very similar to the more expensive C390DD, but with fewer inputs and features? Or is their performance dramatically different in some respect? I don't really need a lot of inputs, or the modular expansion of the C390DD.

I'm holding out to hear the NAD D7050 and D3020 due out soon, but would like to compare to other products as well. Unfortunately, I don't think there is any place I can hear Nuforce or Wadia in my area. Are there any other products in this category I should consider? Also, it looks to me from the press releases like the D7050 is going to be a direct digital product (a la C390DD), but the D3020 is more likely a traditional DAC and Hypex (UCD?) based amplifier stage. Does anyone else have a read on this? I'll likely want to hear them both, if possible.

I suppose I may end up buying several of these with 30 day trial period and letting them duke it out head-to-head in my listening space for who gets to stay. Nominations for contenders are solicited! Should I be trying to get hold of an AVA Media Maestro 50? Trying to keep it under $1200, under $800 would be better and I'm certainly value oriented. There was also another Canadian company selling something similar in the $800 range (shiny white case, if I recall), but I cannot recall them right now.  All input here regarding digital input, PWM amplifiers ("full digital" or "direct digital") appreciated!

[craig in SD]

Lots of views, no replys... here's an update.  Received an NAD D7050 and Wadia 151 this week.  Now auditioning them as fed by SB Touch through Blue Jeans Cables coax, and mated to my Monitor Audio Silver 5i floorstanders.  Spent over 2 hours last night listening to brand new devices.  Initial impressions are that there is definitely a "direct digital" purity and precision to the sound of both--some might even call it clinical.  The Wadia had a more up-front presentation and more rolled-off low end.  I was surprised, but initially preferred the NAD--seems more involving, with a deeper sound stage.  Will definitely be doing more listening in the coming days/weeks.

[dehory]

I'm very interested in your continued thoughts on the D7050. These intriguing units have only just started shipping, and your initial impression is the first I've come across.

I've just sold off my traditional Naim/Spendor system due to an impending move and the realization that I exclusively listen to FLACs and MP3s these days. I'm now looking at different implementations for an Airplay-based networked system. The D7050 would be a particularly elegant solution for me. There are many amp/DAC combos out there, but the D7050 is the only 2-channel amp with Airplay I've seen that has aspirations beyond a bookshelf/2nd system (c.f. Denon DRA-N5).

What made you specifically pick the D7050 and Wadia for audition, and not comparable amp/DAC combos? My long list of these products: Peachtree Nova 125 (and Grand), Wyred4Sound mINT, NuForce DDA-100, Bel Canto C5i/C7R, Core Audio Kratos, Brunoco Diva, Neuhaus T-1/T-2, Emille Ara, Calyx CTI, Leema Elements, Rotel RA-12, Harmon Kardon HK 990, TEAC AI-501DA, QLS QA100, and Onkyo A-5VL.

[craig in SD]

In my price range, the Wadia, NAD, and NuForce are the most readily available PWM amplifiers available in the US.  The Wadia has received very positive reviews across the board, and the NAD is brand new, but likely an evolution of the similar Masters series and C390DD products, also with very positive reviews.  The NuForce has received more mixed reviews (some love it, but others do not.)  These were my top 3 choices for auditioning, while all others are either outside my price range or require an international purchase (and not likely a simple return if I don't like it).

Not all the products you mention are direct digital amplifiers.  I'm pretty sure the Peachtree, W4S, Rotel, and TEAC are not.  I believe these products utilize a more traditional digital-to-analog converter in the same box as an amplifier.  I am specifically limiting my search, for now, to direct digital products, which is not to say they are necessarily superior.  But theoretically, anyway, they have much fewer components in the audio path and therefore fewer opportunities to color the sound.  I'm not just talking the elimination of an analog cable.  The direct digital approach, as I understand it, is to convert a PCM signal to a PWM signal in the digital domain, and feed the PWM signal directly to the input of the amplifier, with a low-pass filter on the amplifier output.  The Nuforce, QLS and Core Audio products do fall in this category.  But the Core Audio Kratos is outside my current budget (despite being manufactured right up the road from me), and the QLS from China just seemed logistically challenging to audition.  The NAD and Wadia products are also manufactured in China, but marketed, stocked, and distributed domestically.  If I don't love one of these two, the NuForce DDA-100 will be the next one I audition.

The NAD D7050 does have a nice set of features for those who are committed to digital audio.  There are no analog inputs, but a variety of ways to get digital signals in.  In particular, the DLNA/Airplay and Bluetooth connectivity are nice additions.  I haven't tried them out yet, except to see that I was able to use WPS to easily connect the D7050 to my secured wireless router.  Some of these features are also available in the less expensive DAC/Amp combo from NAD, the D3020.  I don't recall if Airplay is one of them.

[craig in SD]

Here are some initial impressions I posted on another forum yesterday: the Wadia is nice and detailed, though does seem rolled off in the low end. Instruments are precisely located on a 2D soundstage. The NAD, by comparison, seems much more immersive, 3 dimensional, and engaging. The bass is slightly fuller, but certainly doesn't thump, but there is a definite sense of space with the D7050 that I'm not getting with the 151. The Wadia makes my speakers sparkle. With the NAD, they just disappear. This is some of the highest praise in my book.

The results could certainly be a function of synergy with my speakers. I'm trying to be patient and make sure it's not just a matter of break-in. But every time I sit down to listen to the 151, I can't wait to switch over to the D7050. Last night it was stellar with Reference Recordings and Chesky classical recordings of Copeland and Beethoven, and really, really good with Miles Davis, Cannonball Adderly, Dave Brubeck, Frank Sinatra, Fiona Apple, Radiohead, Muse...

[dehory]

Thanks for the update! Power-wise, how does the D7050's 50 watts (NAD says @ 4 ohms, PR says 8) compare to amps you've had in the past?

You're absolutely right that many of the products I mentioned are DAC/amp combos, and not PWM/"direct digital" amps. An all-digital topology seems far more elegant to me as well (at least, on paper) given a digital music source like your Squeezebox Touch or an Airplay signal. The problem for someone building a new system is that these all-digital choices are all fairly limited in power until you get to the $2.5k price bracket, which in turn restricts the flexibility of speaker choice. Yes, the Wadia reportedly drives Magnepan MMGs, but reviews also suggest it falls short on other tough loads.

[craig in SD]

Agreed about the limited choices for direct digital amplifiers.  Even at $2.5k, the only additions to the list are Core Audio Kratos and NAD C390DD.  I suspect we will see more of these types of products in the coming years, though.

To be fair, I do not have an extensive experience with various amplifiers--there are people here with lots more experience trading out amps in different rigs.  That said, the NAD plays plenty loud in my small space (perhaps 16' x 24' x 12' high, I use about half the room for listening and sit about 7'-8' from the speakers).  I have found that my volume setting is usually somewhere between -20 dB and -8 dB, which may seem pretty high on the scale, until I recognized that the min and max settings are -90 dB and +10 dB, respectively.  So I tend to run between 70% and 82% of full volume.  I guess that does sound rather high...  On my Nakamichi receiver I never turn the volume past about 10 o' clock.  Tonight I tried turning the volume up past 0 dB, and reached uncomfortable volumes with no audible speaker distortion from what I could tell.

I don't think having the volume level set this high is a problem at all, and here's why:

1.  The dynamics are great--there is clearly plenty of power left for transient response, and I never hear any sort of clipping or distortion.  I guess this is what they mean by "clean watts, conservatively rated", which you hear a lot with NAD and some other brands that have resisted the marketing push to sell "more watts."  And as I write this, I recognize that dynamics and microdynamics are actually stellar, and this one thing that sets the D7050 apart from the Wadia 151 and other amplifiers I've had with these speakers (most notably a 100W Nakamichi AV8, as well as a 50W Dayton Audio tripath (not really a fair comparison) and a 50W Emotiva a-100 I tried for a few days.)  And I would say the same comparing this setup to many a system I have heard on showroom floors and living rooms with different speakers and amps.  The dynamics are great, and the frequency response seems flat over a wide volume range.

2.  With the source paused, the speakers are dead silent, even with the volume turned all the way up.  This pure black background is one of the most impressive things about this type of amplifier, IMO.  I noticed this with the Wadia and NAD C390DD as well.

3.  The unit never really gets warm.  It is delivering it's power to the load pretty efficiently.

Power aside, I'm very, very impressed with the detail, channel separation, imaging, and frequency response as well.  I don't have equipment to measure any of this, but the net result is a deep and detailed soundstage with a sense of space around it and an very engaging listening experience, the likes of which I have not experienced with these speakers before.  The more I listen to the D7050 with my Monitor Audio Silver 5i's, the more impressed I am.  I can't wait to rediscover every recording in my collection with it.

All that said, I do have some gripes about the ergonomics:  the touch-sensitive power 'button' is not responsive once powered on (I think the unit is intended to be turned on/off only with the remote, but the touch spot button just feels gimmicky); the remote feels sort of cheap and button labels on it are hard to see, buttons are flush and not easy to find with your fingertips; and the speaker binding posts are not deep enough to accept the banana plugs on my speaker cables all the way.  The overall fit/finish is not bad, but not impressive, either (especially compared to the solid aluminium body of the Wadia 151, or when considered relative to it's own excellent sonic performance.)  The importance of such things varies to each person.  For me, sound quality ranks highest and this unit scores very high in that category.  I'm curious what others will find with their speakers--whether I have some special synergy or whether the amp is an all-round heavy hitter.

[dehory]

I'm curious what others will find with their speakers--whether I have some special synergy or whether the amp is an all-round heavy hitter.

It really seems like you managed to find great synergy without much fuss. I have precisely the same curiosity as you do, and it's a shame that there are still basically no reviews (user or professional) for the D 7050 besides yours. Perhaps the upcoming What Hi-Fi? review for the NAD D 3020 will have some thoughts on the D 7050.

The amp would be driving my main living room system, so my best bet may be a pair of efficient floorstanders. There would be a certain elegance (like you noted) in pairing a direct digital amp with crossover-less full-range speakers like those made by Zu.

[craig in SD]

At some point soon I will try the D7050 with my PSB Imagine B's from another room.  I think they are sonically and electrically pretty similar to my Monitor Audios, but at least it will be another data point.

[ctm]

Any updates? I'm trying the NAD D7050 now with Sonus Faber Concerto's and it rocks. I feel I have to check out the Wadia 151 though to really compare.