Dear Tyll,
I have already ordered several of your amplifiers all the way to Australia. I have been so content with the venerable Desktop Portable (with DAC) thus far that I have even brought it to Spain where I am working for 6 months.
I have tried a variety of sources including analog, and USB (with a small Fujitsu Lifebook UMPC). The most convenient though has been my old Iriver IHP140 but alas the battery is dying. Looking for a replacement with optical out, I found an Edirol R-09 very cheap in Japan. Although designed primarily as a recorder, it plays MP3s or WAVs off a 4Gb card and runs on 2xAA batteries (20hrs playback). Interstingly the sound quality seems better using this and the optical input of the Desktop Portable rather than playing the same file via computer and USB.
So to answer the question of this thread, this has now become my preferred source as it is small and light, and does not require the boot up time of a UMPC. Sound quality is excellent. It is no big deal to transfer files to and from the card.
I am now particularly interested in the Micro Portable with DAC as I think this will complement the R-09 to make a lightweight, hi-fidelity rig.
This is the link to the player, and no I don't work for Roland.
http://www.rolandus.com/products/pro...7&ParentId=114