Digital SPDIF sound via fiber cable on Asus M3N78-EM (nVidia MCP78S)

  I have bought Asus M3N78-EM motherboard for my new HTPC. I'm currently testing it with KnoppMyth R5.5 and installation with KnoppMyth R5.5 worked flawlessly.
  Motherboard specs:

  • Socket AM2/AM2+ - AMD Phenom™ FX / Phenom / Athlon™ / Sempron™
  • Integrated NVIDIA GeForce® 8 Series GPU with HDMI/DVI/RGB
  • Realtek® ALC1200 8 -Channel High Definition Audio CODEC with optical S/PDIF out port at back I/O
  • NVIDIA built-in Gigabit MAC with external Realtek PHY
  • 1 xUltraDMA 133/100/66/33, 1 xExternal SATA 3 Gb/s ports 5 x SATA 3Gb/s ports (Use SATA1-3 for IDE mode.), NVIDIA® MediaShield™ RAID Support RAID 0,1,0+1,5,JBOD
  •   After installation:
  • Onboard Nvidia 8300 GPU worked
  • Analog sound worked
  • Gigabit ethernet worked
  •   Only thing that didn't work was digital SPDIF sound via optical (fibre) cable.
      To enable optical sound you only need to edit etc/modprobe.d/sound file, it needs to have this line:
    options snd-hda-intel index=0 model=6stack-digout
      sound chip on this motherboard is MCP78S as seen via lspci -v command:
      00:07.0 Audio device: nVidia Corporation MCP78S [GeForce 8200] High Definition Audio (rev a1)
    Subsystem: ASUSTeK Computer Inc. Unknown device 82fe
    Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
    Memory at fce78000 (32-bit, non-prefetchable) [size=16K]
    Capabilities: [44] Power Management version 2
    Capabilities: [50] Message Signalled Interrupts: Mask+ 64bit+ Queue=0/0 Enable-
    Capabilities: [6c] HyperTransport: MSI Mapping

        Enjoy your new digital sound.