September 2009

The Nearfield
The Devilsound USB DAC And Channel Islands Audio VDC 9.0
Review By Steven Stone

 I've been thinking about J. Gordon Holt lately. Mostly I've been thinking about Gordon's position on the current state of high-end audio. His position was that neutrality and transparency had been supplanted as the most important criteria for sonic excellence. Instead euphony, or a component's ability to sound “good to me,” was the new gold standard. He felt that it was fool's gold.

I, too, hold transparency and neutrality as the definitive goals for any piece of sound gear. Stu Hegeman's comment that designing "a straight wire with gain" was the ultimate audio challenge still holds true. So how does this relate to desktop computer audio where most of the source material is less than stellar? For me, the same rules still apply. Mediocre recordings should sound mediocre and good recordings should knock my socks off. To demand or expect anything less is eventually going to lead you down the slippery slope to mid-fi mediocrity.

I'll look at two products in this installment of the Nearfield. First we'll explore a fiendishly good DAC, and then a linear analog power supply for the Logitech Squeezebox Duet or Wadia 170 iPod dock.

The Devilsound USB DAC
Priced at only $299 direct from the manufacturer, the Devilsound DAC attempts to deliver exceptional sonics for a mere pittance. Currently Devilsound is shipping version 2 of their DAC. It features a 16-bit non-oversampled D/A converter capable of handling up to 48/16 signal. I could parrot what Devilsound writes about their DAC, but instead I'll give you the link to a detailed technical explanation of Devilsound's design philosophy Devilsound's design philosophy.

The Devilsound DAC is quite small – it takes up less space than a pack of cigarettes (remember those?). It also has both RCA and USB connection cables attached. The good news is that you can't use an incompatible cable by mistake with the Devilsound. The bad news is that you can't tweak the DAC by using a super-premium cable. But isn't the idea of using a +$300 USB cable with a $300 DAC is a bit silly?

Installing the Devilsound USB DAC in my Mac system was simple – I attached its USB cable to a USB output and its RCA plugs to the input of my Reference Line Preeminence preamp. Then I selected the Devilsound DAC from my Mac's sound devices control panel and I was done. The Devilsound has more than adequate output level to support a passive preamp such as the Reference Line Preeminence. Most of the time I used the Preeminence with its volume control set to approximately 12 o'clock.

Naturally, I compared the Devilsound with the similarly-priced ($299) High Resolution Technologies MusicStreamer+.  Differences between the two weren't earth shattering. The Devilsound delivers slightly better depth rendition and three-dimensionality. I'd describe the Devilsound as more tube-like. But this spatial edge comes at a cost- in my desktop system. Regardless of which amplifier or speaker I used, the Devilsound put out a low-level hiss. With my modified Dyna Stereo 70 the hiss is virtually buried under the amplifier's own noise floor, but with both the Accuphase P-300 and Bel Canto S-300 the Devilsound's background hiss is clearly audible. However let me emphasize that audible doesn't mean distracting. You can listen through the noise, just as with tube electronics or LPs. The Devilsound's hiss is not a fatal flaw – it's merely not as deadly quiet as the MusicStreamer+.

Even when compared to a much higher-priced DAC, such as the Bel Canto DAC3, the Devilsound ranks very well. TheDAC3 has a blacker background with no hint of noise, as well as a slightly more dynamic overall presentation. But the Devilsound is its equal in terms of depth, soundstage width, and even low-level inner detail. I was especially impressed with how well the Devilsound matched the DAC3 in terms of three-dimensionality and imaging palpability. Well-recorded lossless music files retained all their spatial information when played through the Devilsound.

The only disappointing aspect of the Devilsound's performance appeared when I played back AIFF and WAV files through the Amarra software plug-in for i-Tunes - the sound didn't audibly improve. I've noticed that Amarra isn't a software panacea. Some DACs, such as the Devilsound and the MusicStreamer+, don't get any better when music files are played back through Amarra while others, such as Empirical Audio's Offramp USB converter, do sound better. Why? I have no idea.

Choosing Between The Devil (Sound) And The Deep Blue Sea
If forced to choose between the Devilsound USB DAC and the High Resolution Technologies MusicStreamer+ DAC I'd be hard-pressed to decide which one I prefer. The Devilsound has the edge in terms of three-dimensionality, but the MusicStreamer has a blacker background.  If I were on an extremely tight budget, the inclusion of both USB and RAC cables with the Devilsound would probably push me in its direction. If I had to run some distance from my computer to my analog preamp, the MusicStreamer+'s flexibility in terms of connection cables would be important. You can't go wrong with either DAC since both deliver excellent performance at a ridiculously affordable price.

Channel Islands Audio VDC 9.0 High Current Power Supply
Digital switching power supplies can be found on many audio devices. They are inexpensive, reliable, but can often induce AC, RF, and digital noise into not only the device they're powering, but also the rest of your audio system. Channel Islands Audio's principal designer and chief poohbah, Dusty Vawter, listens to a lot of analog sources including his FM tuner and phono. He's also a big fan of the Logitech Duet wireless music server. When he put the Duet into his system he immediately noticed the increase in AC noise caused by its wall-wart digital switching power supply, so he built an analog power supply to replace the stock supply, thus the VDC 9.0 was born.

Specifications for the VDC 9.0 can be found on Channel Island's website. It works for either 120 or 240 VAC and puts out 9 volts DC with 2.5 amps capability. The VDC 9.0 is available with an interchangeable connector for either a Logitech Duet or Wadia 170 iPod dock. In both cases the connecting cable is pretty short – only 24”. This is because this is a DC supply and longer lengths of connecting cable would have a negative effect on the actual output.

I ran several different tests to determine how much noise the stock Logitech power supply generates. First I used an Audioprism Noise Sniffer power line analyzer, then the PS Audio Noise Harvester, and finally listened to my Sony ST-120 Fm tuner. In every case it was easy to see that the Logitech power supply was generating AC noise. Then I replaced the Logitech supply with the Channel Islands VDC 9.0. and all the noise vanished. From my tests I have no doubt that the VDC 9.0 generates far less noise than a stock power supply.

So does eliminating a source of AC noise make a difference in the performance of the Logitech Duet? No, yes, and maybe. When I used the digital output from the Logitech Duet I didn't hear any clear sonic differences between the two power supplies. When I moved the duet into another system where I used its analog outputs I noticed a small, but noticeable improvement in its overall sound. The background was quieter and the electronic grain level was lower with the VDC 9.0 than with the stock supply.

But regardless of which system I used, when the Logitech stock power supply was plugged into the same AC line as my FM tuner the quality of the FM tuner's sound deteriorated noticeably. It was as if I had reduced the sensitivity of the tuner's front end by attaching an inferior antenna – background noise went up and my listening pleasure went down.

The Price For Quiet
The Channel Islands VDC 9.0 isn't inexpensive at $279, but is it a good value? If you use the Logitech Duet's digital outputs, as I do, you may question your need for the VDC 9.0, since it makes little improvement in the Duet's sound. But if you use the Duet's analog outputs and if you use an FM tuner in your system you may well find VDC 9.0's ability to reduce AC noise will be audible in both the Duet and your FM tuner's sonic performance. Of course, you could merely unplug the Duet's stock power supply each time you want to listen to your FM tuner... but the Channel Islands VDC 9.0 is a far more elegant solution.