Korg DS-DAC-100m USB DAC/Headphone Amplifier
Full review and laboratory test of the Korg DS-DAC-100m USB DAC/Headphone Amplifier by Australian Hi-Fi Magazine. Free download.

The following equipment review consists of a full subjective evaluation of the Korg DS-DAC-100m USB DAC/Headphone Amplifier written by Jes Roden, but omits the technical analysis.

If you would like to read the complete review, together with a complete set of independent laboratory tests and graphs conducted by Newport Test Labs and a test report written by Steve Holding, click on the graphic at the right, which is a downloadable pdf that is an exact replica of the original pages on which the review appeared in Australian Hi-Fi Magazine, January/February 2017 issue (Volume 48 Number 1).

Korg DS-DAC-100m USB DAC/Headphone Amplifier

This is a slightly unusual review because we obtained the Korg DS-DAC-100m USB DAC and headphone amplifier not for the purpose of reviewing it, but to use it with an editorial project because rather unusually, it has the ability to convert digital music between formats, including to that most stand-offish of formats, Direct Stream Digital. But, once that project was complete, which in the process exposed us the Korg’s very considerable other capabilities, all delivered at a remarkably low price, we thought we'd be remiss in not covering it in its own right.

The Equipment
The Korg DS-DAC-100m is a portable variation on Korg's desktop DS-DAC-100 (which retails at around $549), offering the same performance and features, but in a more pocketable form, and at around half the price.

The smooth plastic case has the USB connection and 3.5mm line output at one end, and a 3.5mm headphone socket at the other. Next to that is a line of nine tiny LEDs, and then two buttons for volume up and down. These are for the headphone output only. The line output is fixed. (The desktop version—DS-DAC-100_has both XLR and RCA line outputs and a full-sized 6.5mm headphone output.)

I really liked that line of LEDs. The right-most one is white and indicates power, while the others specify the sampling frequency: 44.1, 48, 88.2, 96, 176.4 and 192kHz in PCM, and 2.8224 and 5.6448MHz in Direct Stream Digital (also known respectively as DSD64 and DSD128). All that's missing are certain formats that are so high in resolution, and so infrequent in use, that they would seem to be quite wasteful: PCM at 352.8kHz and up, so-called Quad DSD (11.2896MHz or DSD256) and Octa DSD (22.5792MHz or DSD512).

When you are dealing with a computer, audio sampling frequencies are tricky. If you naively plug a DAC into a computer and start playing even high resolution audio using the standard players, you're going to be getting sound at a fixed sampling frequency set in the operating system's audio settings. What you actually want is for the computer to decode the audio from its stored format (FLAC, AIFF, WAV, APE, even MP3, etc) to PCM, to not decode DSD to anything, and to pass these at their native sampling frequencies to the DAC. That requires third-party players… and choosing appropriate settings within them.

With a DAC that clearly indicates the signal it is receiving, such as this Korg DS DAC 100m you can be confident that your settings are correct. It uses a Cirrus Logic CS4398 chip for digital-to-analogue conversion. This provides native decoding of DSD, and multibit oversampling delta-sigma conversion of PCM. The oversampling rates are 128× for 44.1 and 48kHz sampled PCM, less for higher frequencies. That allows CD-standard digital audio to be filtered at 20kHz with no high-frequency phase shift.

Installation requires drivers to be installed on the computer, plus Korg's own AudioGate3 software. Most computer audio DACs conform to either USB Audio Class 1.0 or USB Audio Class 2.0 specifications. Windows handles the first natively (this is limited to 96kHz, 24-bit) while Macs handle both natively (2.0 supports 192kHz). I am not certain that this unit complies with either, since it will not work even on a Mac without the installation of its own drivers. This is likely because of its DSD focus.

Inevitably as new technologies become available there will be a little scrabbling about as companies try to make things workable. Thus it was with DSD, a weird format with which neither of the USB audio standards were comfortable. Most DSD-capable DACs deal with this by faking it: the DSD pretends to be PCM.

Basically, the DSD data is inserted into a PCM container. If fed to a non-DSD DAC it will come out as horrendous noise. But if fed to a DoP-capable (DSD over PCM) DAC, it will be recognised for what it is, extracted from the container and played in native DSD format.
This may sound strange, but it is not unprecedented. Remember DTS-CDs? They have 5.1 channels of DTS packed into the same format as a CD, carried on a CD. Play it in a regular CD player and you get dreadful noise. Plug the digital output of the CD player into a DTS-capable home theatre receiver, and you get 5.1-channel DTS sound.

But it looks like Korg was early to the game and rather than going DoP, it developed its own system for sending DSD over USB. Thus the need for its own driver… even on a Mac.
Once the driver is installed, it can be selected from your player software or from the computer's operating system, and you can happily play back all PCM-based music the way you prefer. But the only way to play DSD material natively (that is without converting it to PCM) is by using Korg's own AudioGate3 application. Using Audirvana Plus on my Mac, it worked fine with all sample rates of PCM up to 192kHz, but DoP simply wouldn't work.

As it happens, while I started and conducted some measurements on the Mac, as is my practice, shortly before settling in to formally preparing this review, I upgraded the Mac's OS from Yosemite to El Capitan. Belatedly I discovered that the Korg driver was incompatible with this—even just plugging in the DAC caused the whole computer to crash and restart. Korg promised it would fix El Capitan incompatibility by June 2016 last year, but at the time of writing had only released a beta driver (Ver1.0.9).

So I installed on a Windows 8.1 notebook and conducted most of the review on that. The Windows installation went smoothly. You just download the latest .zip file from the Korg website, unzip it and run the setup.exe program. From here you install the driver and the AudioGate3 software and, if you want, the User Manual.

Initially, while it was still working with the Mac, I used the aforementioned Audirvana Plus software for PCM content. With Windows I used the latest version of Foobar2000 with the WASAPI and ASIO components installed (these allow the player to bypass the Windows audio systems and interact directly with the Korg driver).

I had been using a DAC with a relatively low-level analogue output voltage previously, so the significantly higher level from this Korg caught me by surprise at first. However it ought to be similar to most CD players.

It's kind of ridiculous that a sub-$400 DAC can sound so good. Nonetheless, that was the case. For the most part I used it with line outputs feeding the analogue input of my stereo. Functioning in this way it provided the levels of musicality, precision and imaging that you'd expect from a DAC costing ten times as much. Indeed, if there was a significant difference between an extremely expensive DAC I was using a month ago and this DAC, it was beyond me to detect.

For example: the Don Burrows Quartet at the Sydney Opera House (CD standard, of course, originating in an analogue recording from 1974) can, inadequately handled, sizzle painfully in the treble. With the Korg DS-DAC-100m it was bright and precise, with the guitar and cymbal interplay gloriously expressive in Sweet Emma, while the drum and clarinet section on the same track had a real presence.

The barely controlled insanity of King Crimson on Cat Food, from 'In the Wake of Poseidon', delivered in 96kHz, 24-bit PCM was first-class in delivery, with the madcap piano smashing appropriately, and a solid, clean bass line.

Mark Knopfler's latest solo album, 'Tracker', in CD standard, was delivered with the subtlety of his guitar fully preserved and his voice sounding just like that of a real person, unveiled.
The live ambience of Tangerine Dream's 'Ricochet', in DSD64, was delivered with the muted percussion occupying a wider sound stage than the physical positions of the loudspeakers, yet with an eerie precision.

Finally, I shall limit myself to describing the audiophile DSD tracks from Blue Coast Records as simply transparent, with the entire recording and reproduction train between me, the listener, and the artists, utterly abolished.

As mentioned, while you can play PCM with your choice of player, you are required to use the AudioGate software for native DSD playback. On Windows computers this gets around the painful process of setting up software for native DSD playback and on a Mac eliminates the need to pay for separate DSD-capable software. If you choose ‘Auto’ for the sample rate in the preferences, your computer will deliver the audio in its native PCM/DSD format to the DAC. You can choose a rate, including DSD64 or DSD128, if you prefer, but this would be silly since it's adding an unnecessary digital format conversion.

Anyway, in use you just drag the music you want to play into the program from Explorer (or Finder). This is going to work best if your music is reasonably well-ordered on your computer. There are repeat and shuffle options, as well as the usual play/pause and skip options, plus there’s a time line which you can click on to choose a playback position. When a track is first played its timeline is just a bar, but after it has been in the library for a while it becomes a chart showing the level versus time, so you can navigate to a point within the track quite sensibly. The software must scan tracks in the background to develop this information.

The headphone performance was good, competent, and able to deliver strong volume levels with a good overall balance to the sound. But it seemed to lack the presence and the immediacy delivered by the line output.

There was one design oversight, though. There was a switching noise emitted by the unit's analogue output—just a moderate click, to be sure, but a click nonetheless—when the digital format of the audio changed. Generally DACs incorporate a mute function to eliminate this kind of thing.

The Korg DS-DAC-100m would appear to be just about the most cost-effective way of getting real DSD decoding (that is, not via conversion to PCM) from a computer. Unfortunately, to get that you have to use Korg's own software for DSD, which might not suit your style. # Stephen Dawson

Korg DS-DAC-100m USB DAC & Headphone Amplifier
Brand: Korg
RRP: $299
Warranty: One Year
Distributor: CMI Music & Audio Pty Ltd

Excellent audio performance
Supports DSD64 and DSD128
Brilliant value for money

3.5mm ‘phone socket
3.5mm line output
Switching noise on format change

A full technical appraisal of the performance of the Korg DS-DAC-100m DAC/Heaphone Amplifier  with test results, frequency response graphs and an analysis of the technical performance, is contained in  the LABORATORY REPORT which is in the pdf version of this review. (Click the RED box above)..