Atom DAC+: Closer Examination

The JDS Labs Element II felt appropriately sized for a desktop DAC/amp combo, and even that is smaller than many others. I knew going in that the Atom DAC+ was going to be even smaller, but even that doesn't help when you pull it out and realize how small it actually is, coming in at ~12.5 x 13.5 x 3.5 cm and weighing just over 225 grams. It would be quite pocketable if it weren't for the AC power adapter and other required cables. The body is entirely made out of ABS plastic, which adds to the lower heft, but also makes it easier to tilt under the weight of cables at the back if not arranged properly. The design language is clean, with a predominantly black color and white legends, including the company name and logo on the top near the front. The product name is seen on the front, with the other side having a switch to choose between two inputs. At its face is a circular indentation surrounded by an LED, which no doubt matches the volume wheel on the Atom Amp+.


A look at the back confirms there are two data inputs in the form of USB Type-B, which I suspect everyone buying the Atom DAC+ will use, and optical. The AC power adapter cable plugs into the jack all the way at the right with or without the switch adapter cable, and certification logos have been placed between it and the other ports. These again all come marked, and the two RCA output plugs are placed on the left, with the right and left channels marked as well. More plastic greets us on the back, where we see four small rubber pads on the corners. These help lift the Atom DAC+, preventing scratches to the case while adding some friction against the resting surface. Notice how the two screws near the front are placed in a raised notch, which slightly shifts the box up for more amenable line of sight to the front while shifting the center of gravity to the back if the internals are weighed uniformly. There are screws underneath each of the pads, which I promptly removed to examine what is going on inside.


Aha, and this time around, it is the lid that comes off for a closer look at the more useful side of the PCB. It comes marked accordingly for the Atom DAC+, confirming this is indeed a JDS Labs creation and not a common design. The original Atom DAC came about after what seemed to be a fervor among those who bought and liked the original Atom Amp, and understandably fell prey to the AKM factory fire late last year, as did many other products. Instead of just changing the DAC chip, which the company seemingly did not even have to do, JDS Labs went with the ESS Sabre ES9018K2M 32-bit reference stereo DAC, but changed the output stage to allow for even lower SNR and THD, which is a bold move considered the ES9018 is infamous for being very sensitive to any circuitry changes. Interestingly enough, during this R&D process, there was a particular step that effected second-order harmonics as-is and boosted third-order harmonics to where some people would absolutely scoff at the worse SINAD values (~65 dB vs. 112 dB), but it remains an experimental firmware file for those wanting to get something more akin to a tube DAC/amp.

The addition of the optical input is new too, as are the many other firmware options, which has been noted with the Element II, too. What has remained unchanged is the XMOS U30870C10—an XMOS XU208 USB bridge with the xCORE 32-bit multi-core microcontroller that has been used successfully for USB audio Class 2 implementations, though it now passes up to 32-bit, 384 kHz PCM playback to the DAC, in addition to DSD64 to DSD128 playback support with the currently shipping firmware v1.8.9. Effectively, the Atom DAC+ has better ratings across the board over the original, already popular Atom DAC, including +/- 0.12 dB on the frequency response, instead of +/- 0.15 dB, SINAD of 112 dB, instead of 110 dB as a result of the THD halving to < 0.0004% and SNR increasing from >115 dB to >117 dB, and USB jitter dropping from -124 dB to -131 dB.