Unfortunately, adjusting alsamixer has no affect on the S/PDIF output (sometimes I dont think too hard as it cant be adjusted).
For some reason, just recently the S/PDIF signal from my MD to my receiver is 'clipping' my receiver, but only at 'loud' points in the audio stream. I havent had this problem until the last month or so. It only occurs with some movies (dvd rips) and sometimes in mythtv.
Is there an 'internal' audio level for the media players that can be adjusted?