It's been said that sonic contribution of a typical DAC would be 30% DAC chip, 30% analog output stage, 30% power supply, and 10% for the other parts combined. Your typical consumer piece of equipment often comes with cheap wall-warts or switching power supply which in itself is notorious for noise - which is measurable and often heard. Psycho-acoustically we perceive this as "grunge" and "edginess" rather than higher noise floor.
Soon after our review of the Calyx DAC 24/192, kind readers were suggesting that the DAC may be better treated with an outboard power supply. During our original review, the Calyx was powered primarily by USB. It uses an energy storage and regeneration circuit, internally generates 12v voltage rail and outputs 6.5v over its balanced XLR outputs from USB's mere 5v. The included wall wart was tested and found indifferent in terms of sound quality. We were equally curious whether we can still improve it excellent sound quality so we contacted Kingrex for a review of their latest Power Supply Unit, which is in its Mark II incarnation.
The 5V version would power the Calyx DAC 24/192, Squeezebox Touch, Onkyo ND-S1 iPod Transport, etc. The 9V version would power a Wadia 170i/171i Transport, Squeezebox Classic/Duet, M2Tech EVO. 12V version also available.
Inside the PSU Mk2 there's a 48VA toroidal transformer, a regulated power-stabilizing circuit with 8 capacitors, 5 x 2200μF at AC input stage and 3 x 4700uF at DC output stage. 6N Furukawa PCOCC wiring through out. The unit has a 3 pin Neutrik DC connection on the PSU side to DC jack (electronic side). The included DC jack is a 5mm external, 2mm internal type, which is actually too short for Calyx's input. We had to modify it by cutting the original jack out and replace with a longer one. If you plan to use the PSU with the Calyx, please request a longer DC jack from Kingrex.
The Calyx has a selector in the back that switches between USB power and 5v DC, so it is easy to compare the effect of two power sources with out having to match levels or interconnects etc. There was a soft "click" when changing the power source and that's about it. During this test we used Wireworld Platinum Starlight USB cable whose unique feature is the isolation of power leads from data conductors.
Results? First was Bill Evan Trio's Waltz for Debby in 24/192kHz format. To get the cymbals in this recording right is one of the test we constantly use to fish out digititis so common in lesser equipment. Cymbals should bite, but at the same time never harsh. There should be air with nice natural decay. Both USB power and PSU performed equally well. We also couldn't hear much difference on the piano nor the softish acoustic bass. We were quite impressed how clean the Calyx's USB power regulation is. Next up were Herbie Hancock's Imagine Project and Manu Katche's Third Round - both excellent modern-day jazz recordings with serious bass and drums. Now the Kingrex/Calyx combo proved to be something the Calyx alone always wanted to be!
Deep bass now has fundamental we never thought missing. Subjectively, we felt that the low end extension extended down another octave or so. It is also ironic when you have more infrasonic reach, you feel you have more "air" as well, even though the upper frequency range is more or less the same. With air, you have a better sense of where the images are in the sound field. Room ambiance are now better portrayed. The soundstage becomes more three dimensional. Slam and weight were also noticeably better with more visceral impact without muddying the mid-bass. Calyx was a little short on pace and rhythm last we tested it, but now with the Kingrex PSU Mk2, the DAC can now really boogie. The combo closes the gap with our reference Weiss DAC 202...much closer than before.
We also have on hand a Squeezebox Touch, which we upgraded with a Teddy Pardo Power Supply and found it to be a notch better than stock wall wart. We did tried the Kingrex on the Touch and thought it offered the same level of performance as Teddy's (tighter bass and extended highs than stock). Just a caveat that the magnitude of improvements are not as significant as the Calyx's but worth the upgrade if you opt for best possible sound from the Touch.
Highly recommended.
