I thought you'd like to know what I found. I upgraded SuSE from Pro 9.3 to the retail 10.0. Afterwards, playing .ogg files resulted in silence (and no error message), but playing a .wav file worked.
I fixed it under kmix, under the Sitches tab, by selecting (i.e. turning the radio button yellow) the item called "IEC958 In Monitor" (my guess is that it became unselected as part of the upgrade. Kmix says my soundcard is a "C-Media PCI CMI8738-MC6".
Thanks for your time.