What SW do you plan to use on platop side to play music that 'came through USB'? Do you have any particular program and/or protocol in mind?

I don't think USB can supply at least 1A@12V (IIRC) needed by empeg, probably more during disk spin-up.

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green