But there is one thing missing: There is no signal at the spdif-out of the usb-sound-box (7.1 Channel USB Sound Box DA-70800 by DIGITUS). Only Speakers-out works. In alsamixer ist nothing to be found to activate / deactivate spdif-out.

Just want to use it as USB-SPDIF-converter to let my old Sony Esprit DAT do the DA-conversion. It sonds a little better then the no-name-usb-box. And a real usb-DAC shall come later.
The same configuration works fine with my Lubuntu 12.04-Netbook and Deadbeef. So it is no ALSA-problem with this box in general.

Have you any idea to get it running also in raspyfi.

Thank you so far

Thomas

PS:
Just had some time to play a little more with raspyfi.
After booting the rasp the usb-box connects to the DAT (display-info on the DAT). After starting music via GMPC the connection breaks immediatly. By the way, the played flac- files are 44/16, the DAT can handle 44 and 48kHz. So this shouldn't be the problem.

A second problem (I first didn't hear it listening to some rockmusic, but later with some classical stuff) is the pemanent low-level pop/click-sound on usb box analog out (not on the rasp's analog out). Couldn'fix ist with http://www.raspyfi.com/raspber.....-audio-fix (both with the usb-audio-fix and the "update for samba-users".
The way to fix it was andrejg's posting on the same thread: "The only workaround I found is dropping the USB speed to 1.1 via dwc_otg.speed=1 in /boot/cmdline.txt and forcing MPD output to 16/44.1 via format "44100:16:2" in /etc/mpd.conf"
So at least I can enjoy 44/16 without pops an cracks from the analog out of the usb box.

Still looking forward to your final release and wish you good luck with this project.

Thomas