Review: Devilsound DAC

Whether factory designed or strategically pieced together by the enthusiastic tinkerer, many people use their computers these days as ‘media centres’ (amongst other things) to play back CDs and assorted other audio files. But very few people who do this ever stop to consider the fidelity of their host computer’s audio card. Most are simply content with the sound quality, provided “signal comes out.” But to some of us, this isn’t enough; the fidelity of the audio signal is important, even though we don’t always know how to bypass the computer’s standard outputs. If, like me, you’re still harbouring older audiophile-style amplifiers devoid of digital inputs, and you’re using them to replay audio from your computer, the Devilsound Labs DAC may be just what you’re after.

DEVILISHLY SIMPLE

The Devilsound DAC takes a digital signal from any USB port on your computer and converts it to analogue RCA. This sounds simple enough, and at first glance the DAC looks for all the world like a standard USB-to-RCA adaptor. But it’s the small aluminium box toward one end of the cable that sets it apart from your average, run-o-the-mill connector.

A USB to RCA audio transfer system isn’t the simplest thing to devise, especially one that sounds good. Firstly, there’s the small matter of D/A conversion, of course, which in the case of the DAC, is handled by the electronics hiding inside the tiny black box. Then there’s the problem of providing a high-quality audio signal in a miniaturised format, at a price that won’t set you back a few week’s wages. But one of the main hindrances to a quality audio streaming via USB is the notoriously dodgy power it supplies. Ideally, a USB 1.1 or 2.0 port should provide a constant 5V of DC power. Unfortunately, this can fluctuate wildly, with stability further compromised by other USB devices potentially on the same port as your audio. Mice, keyboards, and especially hard drives can dirty the power signal and grossly affect the quality of any audio signal being distributed via the same bus. To combat this, Devilsound uses a fast DC-DC converter to regenerate the USB bus power to provide positive and negative 6V power rails, which it then down-regulates to a predictable ±5V. Without this stable power supply, it would be impossible to provide anything close to high quality D/A conversion.

Actual digital-to-analogue conversion in the DAC is provided by two Analog Devices AD1851 chips, running in ‘non-oversampled’ mode. In the audiophile world, non-oversampling DACs are de rigueur – most notably because they use analogue filters rather than the potentially harsh algorithmic or DSP-based digital filters. Non-oversampling devices aren’t technically as accurate, but oh boy do they sound good. (For a detailed explanation of the DAC’s inner workings, head to Devilsound’s website: www.devilsound.com – rarely does a manufacturer divulge such information and it’s refreshing to see such transparency in the audio market.)

Adding to the DAC’s audiophile credentials is its use of Eichmann RCA connectors, which are as good a connector as you’re likely to get – incidentally, these are manufactured in Australia. Simply put, if you’re into blue-ribbon cabling and connectors then these are the duck’s.

THE DEVILSOUND

The DAC works brilliantly and the setup couldn’t possibly be simpler. But I’ll be brutally honest here; the audio from the DAC isn’t something I’d use for serious editing work. Not because of the sound quality mind you, but for the unfortunate restriction of its 16-bit word lengths. This noticeable drawback, to be fair, is due to the requirement of 24-bit audio-via-USB requiring custom drivers, and since one of Devilsound’s primary objectives was for the DAC to be truly ‘plug & play’, custom drivers were out.

Despite all this, the Devilsound DAC sounds incredibly pleasing to the ear. The top end is smooth and unobtrusive, and the soundstage offers depth alongside definition; it’s a remarkably pleasant playback path. I stacked the DAC against various convertors from RME, Digidesign, MOTU and Presonus – all at least five times the price of the DAC. And I’ve got to say it sounded very sweet. For a ‘listening’ system, i.e., one that you’ll have playing for appreciation of recordings, the DAC will be very hard to beat.

SYMPATHY FOR THE DEVIL

For a further peek into the ethos behind the DAC design, I spoke to Jonathan Edwards from Devilsound Labs. Jonathan is the chief technical officer for the company and my first question to him was why non-oversampling methodology was used…

Jonathan Edwards: I first heard about the trend towards non-oversampling DACs almost 10 years ago. Then a year or two ago, I decided to build a better DAC for my computer, and discovered a whole community of people on the internet building similar systems. I was struck by the fact that ‘N.O.S.’ converters are often described as clearer and less harsh, and that they can be designed in a number of different ways. The idea with the Devilsound DAC was to take a circuit architecture that many people preferred sonically, build it as small as possible while still using high quality components, and make it super easy to use.

BW: So why keep access to the circuit design open?

JX: We ultimately got in this business to listen to better sound, and trying to find the best possible designs. It seems that the way to get there from here – the next logical step – may well be through cooperating rather than competition.