Sometimes, a full-blown multi-channel rackmounting interface is just too cumbersome and inconvenient for the task in hand. For example, if mixing or editing material on location, or for replaying material to a client, all that's really needed is a high-quality stereo output. The built-in audio facilities on laptops can be a bit iffy in quality terms, and sometimes balanced line-level outputs are required in any case, or the headphones need a bit more 'welly' than the laptop's amp can manage. On such occasions, a compact high-quality stereo D-A converter, fed from the laptop's USB connection, may be a better option — and there are certainly plenty to choose from!
Two recent additions to the list of potential candidates come from Korg's hi-fi division: the DS DAC100, and its pocket-sized mobile cousin the DS DAC100m. Both units are USB 2 bus-powered devices, and they share the same core technology, supporting all standard PCM audio formats up to 24-bit, 192kHz, along with 1-bit DSD audio files at both the standard 2.8224MHz, and the double 5.6448MHz sample rates — thus ensuring compatibility with Korg's MR-series portable DSD file recorders.
To minimise interface jitter, the USB connection employs the increasingly common 'asynchronous transmission' mode whereby the converter clocks the audio data out of the computer, rather than being thrown data whenever the computer gets around to it! The converter hardware in both models is built around a Cirrus Logic CS4398 delta-sigma DAC chip with a claimed 120dB dynamic range. Unfortunately, Korg's implementation falls short, delivering around 105dB in practice.
A dedicated ASIO/Core Audio driver (currently v1.0.5) is downloadable from the Korg web site, and is compatible with Windows (XP onwards) and Mac OS X (10.6 and later). A bespoke media-player-cum-conversion-software program called AudioGate 3 (currently at V3.01) is also available and can be set up to convert common audio file formats (MP3, WAV, etc.) to the 5.6448MHz DSD format in real time, should you want to use the converter's DSD capabilities throughout — although the converter is quite happy to receive standard WAV files too. I won't go over the supposed benefits of the DSD format here, as I covered this ground in my review of Korg's MR1000 and MR1 file recorders back in SOS March 2007 (http://sosm.ag/mar07-korgdsd).
Stylistically, the desktop DS DAC100 model is very 'nouveau hi-fi', with an unusual lozenge-shaped black case and conical brass spiked feet. The front panel sports a quarter-inch headphone socket and associated large volume control, plus some miniature LEDs to indicate the current sample rate. Some 'zipper noise' (low-level glitching) was evident when changing the volume setting quickly, but the headphone output provides 85mW per channel into headphones with an impedance of 32Ω or more, and there's plenty of level available for all normal headphones. Around the back, a standard B-type USB 2 port is accompanied by a pair of unbalanced gold RCA-phono sockets and two XLRs for the analogue line outputs. The maximum line output level in both cases is +6dBV or +8dBu — which is typical for a hi-fi product, and the same as a standard domestic CD player. Although the symmetrical, electronically balanced, XLR outputs are way below the peak level expected in a professional balanced audio system, most active monitors should be sensitive enough to cope reasonably well.
Given its diminutive size, the little DS DAC100m model necessarily has reduced connectivity. A mini-USB port and 3.5mm stereo analogue line output socket are located on the rear panel, and a 3.5mm stereo headphone output is present on the front, along with a pair of inc/dec volume push-buttons. A row of miniature LEDs again indicates the source sample rate, and the technical specifications are identical to the larger model, with the same maximum levels for the headphone and line outputs.
There is a surprising number of low-cost stereo USB D-A converters on the market, and many sport considerably more versatile feature sets than these two Korg models. However, the ability to handle DSD files is unique at this price, and both units are well-built and perform satisfactorily for the price.
DS DAC100 £479.99; DS DAC100m £347.99. Prices include VAT.
DS DAC100 $599.99; DS DAC100m $349.99.