Sound
From LinuxMCE
Sound FAQ
KDE mixer (Kmix)- usually accessed from the mixer button on the KDE desktop's volume control- does not always properly control the SPDIF (S/PDIF, Toslink) output. This is certainly true of the sound chip ALC889A. To control the SPDIF output you can use the command line, text-based alsamixer program, and watch the red laser switch on and off. Don't look straight into the output of the SPDIF optical port! Instead put a piece of paper behind it or reflect the light off your finger.
Once you've used alsamixer to get your sound setup right, you can use alsactl store.