USB input is TE8802L - based, which is good, but NOT compatible with Linux computers or any other Linux-firmware-based gear, like for instance, the squeezebox toux with the enhanced digital input app (which does support async usb to other DACs), and there are certainly other nice transport that are linux based. That is a real drawback. See this thread for the discussion:
http://www.head-fi.org/t/609062/te8802-asynchronous-dacs-on-linux-and-squeezebox-touch-supported-with-triodes-app-for-the-sbt/15#post_8428138
And write TEAC and GFEC as well as your seller, as suggested in the mentionned thread, as pression of many will help to push them to finally develop a driver!!!

I suggest a mail as this example, if you eventually consider buying such a DAC.
Mail it to av-tsc-ip-sales@teac.com and custser@teac.com :
Dear TEAC-support team, I am wondering, if the USB-input of UDH01-S is Linux compatible. My goal is to buy a DAC, that I can connect to a Linux-computer over asynchronous USB. However, as far as I read, the USB-input is based on the TE8802L - chip. And this is said, not to be Linux compatible. Can you eventually provide for a suitable driver? As for the rest of features, the UDH01-S really looks promising. Thank you, sincerely yours......

This was on my list for upgrades...

7/15 Follow up - the TEAC unit developed some type of glitch allowing it to randomly flip back to the PC speakers despite the DAC lock still being illuminated. To resolve the problem you had to unplug and reinsert the usb cable. TEAC was less than responsive in helping - despite doing everything thing I could imagine including changing PCs and cables, I was forced to return the unit. Fortunately it was bought from Dedicated Audio so there weren't any issues in returning it.

I have replaced it with a demo PS Audio Digital Link III which has performed beautifully without the slightest issue. The software to connect via usb to the PC is internal and requires nothing on the user part. The build quality is much more solid than the Teac but I have been hard pressed to hear any sound improvement. There are still PS Audio units available for $500 (same price as the TEAC)