Digital audio sound on MSI Media Live

[GyroTech]

Hi all,
  I have an MSI media live that I plan to use with MythTV soon. In the 
initial setup though I am unable to get any of the digital audio outputs 
working, this includes optical, s/p-dif coax, and hdmi. The analog 
outputs (phono and 3.5mm jack) both work fine however.

aplay -L lists only one problem with the devices:

iec958:CARD=NVidia,DEV=0
      HDA NVidia, ALC883 Digital
      IEC958 (S/PDIF) Digital Audio Output
null
      Discard all samples (playback) or generate zero samples (capture)

Can anyone help with this, or suggest a good starting point??

Thanks,

GT