Comment 2 for bug 1243728

http://www.via.com.tw/en/products/audio/codecs/vt1828s/

2 independent 16/24-bit S/PDIF TX Outputs supporting 16/20/24-bit, 48K/96K/44.1K/88.2KHz sample rate

http://www.asus.com/Motherboards/P7P55DE_PRO/#specifications

- Coaxial / Optical S/PDIF out ports at back I/O

do your motherboard have any onboard hdmi connector or internal spdif out header in addition to the coaxial spdif ?

you may need to use hda-jack-retask to change the pin default of node 0x2d from HDMI to optical spdif out

Node 0x0e [Audio Output] wcaps 0x611: Stereo Digital
  Control: name="IEC958 Playback Con Mask", index=0, device=0
  Control: name="IEC958 Playback Pro Mask", index=0, device=0
  Control: name="IEC958 Playback Default", index=0, device=0
  Control: name="IEC958 Playback Switch", index=0, device=0
  Control: name="IEC958 Default PCM Playback Switch", index=0, device=0
  Device: name="VT1828S Digital", type="HDMI", device=3
  Converter: stream=8, channel=0
  Digital:
  Digital category: 0x0
  IEC Coding Type: 0x0
  PCM:
    rates [0x5e0]: 44100 48000 88200 96000 192000
    bits [0xe]: 16 20 24
    formats [0x1]: PCM
  Power states: D0 D1 D2 D3
  Power: setting=D0, actual=D0
Node 0x0f [Audio Output] wcaps 0x611: Stereo Digital
  Converter: stream=8, channel=0
  Digital:
  Digital category: 0x0
  IEC Coding Type: 0x0
  PCM:
    rates [0x5e0]: 44100 48000 88200 96000 192000
    bits [0xe]: 16 20 24
    formats [0x1]: PCM
  Power states: D0 D1 D2 D3
  Power: setting=D0, actual=D0

Node 0x2d [Pin Complex] wcaps 0x400701: Stereo Digital
  Control: name="HDMI Phantom Jack", index=0, device=0
  Pincap 0x00000090: OUT HDMI
  Pin Default 0x185600f0: [Jack] Digital Out at Int HDMI
    Conn = Digital, Color = Unknown
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0x40: OUT
  Power states: D0 D1 D2 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0e
Node 0x2e [Pin Complex] wcaps 0x400701: Stereo Digital
  Control: name="SPDIF Phantom Jack", index=0, device=0
  Pincap 0x00000010: OUT
  Pin Default 0x074411f0: [Jack] SPDIF Out at Ext Rear Panel
    Conn = RCA, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x40: OUT
  Power states: D0 D1 D2 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0f

post the pulseaudio verbose log

https://wiki.ubuntu.com/PulseAudio/Log

 ports:
  analog-input-microphone-front: Front Microphone (priority 8500, latency offset 0 usec, available: unknown)
   properties:
    device.icon_name = "audio-input-microphone"
  analog-input-microphone-rear: Rear Microphone (priority 8200, latency offset 0 usec, available: no)
   properties:
    device.icon_name = "audio-input-microphone"
  analog-input-linein: Line In (priority 8100, latency offset 0 usec, available: no)
   properties:

  analog-output: Analog Output (priority 9900, latency offset 0 usec, available: unknown)
   properties:

  analog-output-headphones: Headphones (priority 9000, latency offset 0 usec, available: unknown)
   properties:
    device.icon_name = "audio-headphones"
  hdmi-output-0: HDMI / DisplayPort (priority 5900, latency offset 0 usec, available: unknown)
   properties:
    device.icon_name = "video-display"
0 sink input(s) available.