Just saw this on Audiogon, it's another option for using the M2Tech HiFace w/o a battery created by Paul of Tube Audio Design fame:
Introducing the Tube Audio Design Jitter-JabberIf you research USB to SPDIF adapters you will find information concerning external power supplies for the adapters that drastically improve how analog smooth the D/A occurs. The main issue is standard USB +5V power is loaded with switching noise - under HiFace load my Macmini produces 1.5V of supply hash - 30% noise (see scope picture)! The past year I have been designing a pure DC supply for my HiFace. For a while I was going the battery route with an automatic sleep time charger, last month I finally figured out how to do it battery free! The Jitter Jabber is triple regulated, 1500mV of USB supply hash is completely smoothed out to produce nearly immeasurable noise flat +5VDC (2nd scope picture). To the ear you will notice improvements in analog smoothness that places your favorite DAC many steps closer to analog LP sound. Bass sounds stronger, midrange more lifelike, all the way around you will notice the difference using the Jitter-Jabber between your computer USB and HiFace (or other favorite USB>SPDIF adapter).
Finally a battery free USB powered way to provide pure noise-free DC to your USB audio adapter. The Jitter Jabber circuitry is housed inside a small 4" die-cast epoxy potted black metal box with attached 3-foot input and 3-foot output gold end USB cords. I started selling separately a BNC attenuator HiFace BNC to DAC connection kit, this set of adapters places a 16db attenuator between the HiFace output and your DAC BNC data input. This eliminates the need for a coaxial data cable, just use the attenuator kit to fix the HiFace on the back of your DAC, feed the Jitter-Jabber cable to the Hiface.
http://www.audiogon.com/cgi-bin/cls.pl?dgtlconv&1315079828&/Tube-Audio-Design-Tad-jitter-jabber-usbI have no affiliation with TAD, in fact I'm eagerly awaiting the arrival of my new custom black ART Legato.....
