Outboard DACs

It seemed like a brave new world back then. It was early 1999, DVD video had been on the market for less than two years, and already audio people were seeing the possibilities – music in the home at 24-bit, 96kHz linear PCM, with the potential to knock CD audio into a cocked hat. Alongside the small flurry of music DVD discs that were released with 24/96 audio came the first outboard DACs capable of exploiting this high-resolution material. One of the very first companies to take the challenge was MSB Technology, a digital audio specialist based in California. Its Link DAC was something of a giant-killer, at $350 an affordable external D/A converter with decode capability up to 96kHz, and good wholesome sound playing CDs too. This was all before the diversion of DVD-Audio, which tried to add multichannel audio to DVD-V’s stereo 24/96 spec, and which along with SACD, only served to confuse and fragment the market. Yet out of this false start came renewed interest in the standalone D/A converter, and many audiophiles started experimenting with high-bit decoders and upsamplers, in the process hearing new musical qualities from CD’s 16-bit audio.

MOST SIGNIFICANT BIT – UPDATED
Scroll on to the present day, almost ten years later, and we have MSB Tech’s latest outboard DAC, packed in a similar case as the original Link DAC. Inside though, lies a very different technology story. MSB has continued to innovate since 1999, this time through developing its own D/A converter modules and digital filter. Compare this with the larger body of audio manufacturers who base their converters on off-the-shelf chips.
   MSB Technology has returned to older conversion practice recently, namely a multibit resistor ladder architecture, in contrast to the delta-sigma systems found in most of today’s DAC silicon. At the front end, in place of the Burr-Brown DF1704 filter it once relied upon, is now a DSP-based filter, with the potential for user-changeable filter coefficients. This feature alone can reinvent the sound of the whole converter as I found later. Rather than use clock data from the digital input signal, MSB recreates its own clock, with a FIFO buffer to maintain data synchronisation.
   The Power DAC MSB Gold 4, to give it its full name, is actually a pared-down version of the company’s flagship Platinum DAC III, with fewer features and some internal economies, in the name of making the DAC available at a lower price than the Platinum DAC III. For example, it uses two mono DAC modules (against the Link III’s four in dual-differential), and has no panel display.
   Unusually, it takes DC power from internal batteries in a bid to augment sound quality, with an outboard power supply box serving as battery charger.
   It includes four digital inputs which are designed to auto-switch to an active source, with no front panel switches to manually select an input. In fact, the only control on the front is one marked Play Mode, which puts the DAC into battery power instead of ‘charging’ mode. Those inputs comprise AES, coaxial S/PDIF on RCA, Toslink optical, and a proprietary MSB Network connector. This takes an RJ45 plug from a Cat-5 cable, and is used by MSB to transfer up to eight channels of digital audio at 32/192 resolution, an impressive feat. It’s also with this link that MSB DAC’s are able to take 24/192 audio from DVD-Audio players – after MSB has retro-fitted its MSB XPORT interface into a player.
   Unlike the original Link DAC in its ‘pizza box’ folded steel box, the Power DAC has a weightier feel. The mass is contributed, no doubt, by the presence of five sealed lead-acid batteries inside!

DEFAULT COMMENDATION
Taking an AES balanced digital feed from a dCS Verdi CD transport, the Power DAC quickly assured it was a clean and classy-sounding converter. Like the Link DAC of yore, it had a smooth, tidy sound, free of treble emphasis, and could cast a relatively deep soundstage, if not as wide as the best in class. Rhythmic flow and timing were spot-on, and the Power DAC had a sense of spatiality that erred on the dry and tight side, with little bloom or overhang in the bass. In overall tonality, it showed some of the midband timbral vibrancy and treble kindness of a good analogue source. In all, a commendable performance, but one not too far removed from the sound of a comparably-priced, well-sorted CD player. Like many otherwise fine-sounding modern digital sources, it could seem a little too ‘tamed’; a relatively safe sound that wouldn’t scare the horses.
   And then I started playing with the filters. In one (admittedly not-so-very-easy) step, the Power DAC was transformed into a D/A converter that will have obsessive tweakers in second heaven, and music lovers rooting through their CD library. As discussed in ‘Filter Fun’ [p45], most of the alternative filters seem to be based on relaxing the sheerness of the familiar brick-wall filter, potentially increasing HF artefacts from out-of-band images but with a trade toward a more ‘relaxed’ flowing sound. With the ‘Temporal’ filter, for example, I heard a much opened and widened sound from Call of the Valley [EMI 832867], with santoor and flute sounds appearing from far beyond speaker boundaries. The bass tabla could be heard clearly sliding in pitch as the sound blossomed then decayed after being struck.The downside here was a mildly forward sitar.
   Loading the ‘Lanczos3’ filter, I heard incredible low-level detail dredged from Tori Amos’ ‘Crucify’, hearing the double-tracked main vocal gliding in steady unison while the explosion of low drums rolled out into the room like an unfolding blanket. ‘Pentangling’ from The Pentangle – this time through the ‘HF Dither’ filter – revealed a visceral thwack of strings on plucked bass as two acoustic guitars set left and right interplayed, making a rhythmically fresh sound for the ear to follow. By this point I was convinced: here was an audiophile DAC in the premier league of performance, providing the fabled open window on to the recording studio.

RAW ATMOSPHERE
As testament to the ‘fresh and real’ aspect of the MSB Power DAC when using custom filters, the UK premiere live recording of Shostakovich 8th symphony [Mravinsky, Leningrad SO, BBC] was heard brimming with atmosphere, full of micro-details from orchestra and audience that could truly transport you to the evening. Even the moments between movements had ambience that could creep up on you, with the spine-tingling hushed presence of hundreds of (mostly quiet) people in the room, holding their collective breath.
   Incidentally, it’s worth mentioning that I didn’t hear any night-and-day differences between running the DAC in charging mode or entirely unbridled on DC batteries.
   The hardest part was deciding on a filter to suit all moods. I liked the low-level resolution of ‘Lanczos 3’ but had some misgivings about its bass over-richness on pieces such as ‘Echoes’ [Pink Floyd, Meddle]. And ‘HF dither’ filter could (and perhaps more so than others), seem to sound a little fragile on high female vocal. But whichever you try, the reward is a sound replete with freshness and free of constriction.

VERDICT
Still not a cheap upgrade at over £3000 in the UK, the Power DAC nevertheless has an inviting, analogue tone in standard filter mode. Get your tweaking hat on and try some other filters. You could be in for a treat, providing your personal taste and partnering amplifiers don’t object to a little more ‘shine’ accompanying its open, freeflowing and impressively detailed sound.

Originally published in the April 2008 edition