So, you are testing only over SPDIF output, right?
Yes, I'm only using SPDIF output!
Looks like the SPDIF status bits has been reset by some reason. Try to restore via iecset program included in alsa-utils package, e.g. iecset original on iecset category 0x02
I tried this and didn't notice any difference.
If this doesn't help, try to unload sound driver once, remove (or backup) /etc/asound.state (which might be in a different path depending on the distro), then load sound modules again. This will restore the default SPDIF status. Unmute / adjust mixer setups appropriately after doing this.
I also tried this but didn't notice a difference but however I noticed a workaround to this problem that might be related to deleting the asound.state (debian places it btw to /var/lib/alsa/asound.state): now the regular audio works via SPDIF once again if I first play a file with digital preencoded audio. Ie:
-Boot with 2.6.36-rc5 -Start kaffeine -Play mp3 file -> no sound at all via spdif -Play mkv file with 5.1 sound -> sound ok -Play mp3 file again -> sound ok! -Exit kaffeine & restart kaffeine or vlc -Play mp3 file again -> sound ok!
Unfortunately the fix isn't permanent because after reboot I cannot get regular sound via spdif until I have once played a file with 5.1 audio track.
Yours,
Aki