I've got a MSI K8N Neo2 mainboard with an NVidia 250 chipset, including an audio driver: 00:06.0 Multimedia audio controller: nVidia Corporation nForce3 250Gb AC'97 Audio Controller (rev a1) The machine is connected to a Logitech speakerset via a fiberoptic cable in the IEC958 port. On Windows, i've configured it to output sound via that port and it works great (DD5.1, DTS etc. when watching DVDs). On Linux, i have been unable to get *any* sound output via the IEC958 port. Sound output works fine via any other output (generic headphone audio jack). This most likely a configuration issue, but it'd be nice if we eventually get a GUI for this. Perhaps via GStreamer?
After a little reading @ http://www.alsa-project.org/alsa-doc/doc-php/asoundrc.php?company=Generic&card=Generic&chip=Generic&module=Generic it turns out i just had to change the "defaults.pcm.device" in /etc/alsa/alsa.conf from "0" to "2". It now outputs via IEC958.