Note: This is a followup to this old thread from the SLS forum - where I couldn’t post my solution due to a vacation and the forum merge.
I am using “model=6stack-dig” in /etc/modprobe.d/sound and unmuted everything in KMix (or alsamixer).
5.1 Sound via optical cable on openSuSE 10.3 works like a charm if you simply go to Kaffeine (or whatever you use) and set the audio settings to passthrough - this way, the DTS or Dolby Digital or whatever you got on your DVD will be put through to optical.
speaker-test -c5 (or 6) will not work, because it is playing WAVs which only have information on front left and front right in them and not re-wrapping them into a AC3 stream with channel information for the amplifier.
Thanks to the guys on the alsa IRC channel, I got my system running in less then 5 minutes - compare that to the three days I tried different combinations of alsa versions, openSuSE betas and so on …
Thanks for the help (in the other thread)