Comment 11 for bug 1120853

it is driver bug to create digital spdif in device when pin default is [N/A]

try latest alsa driver

https://wiki.ubuntu.com/Audio/UpgradingAlsa/DKMS

card 0: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital]
   Subdevices: 1/1
   Subdevice #0: subdevice #0

Node 0x1c [Pin Complex] wcaps 0x40020b: Stereo Digital Amp-In
  Control: name="IEC958 Capture Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=0, ofs=0
  Amp-In caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-In vals: [0x00 0x00]
  Pincap 0x00000020: IN
  Pin Default 0x41c5f160: [N/A] SPDIF In at Ext Rear
    Conn = Optical, Color = Other
    DefAssociation = 0x6, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x20: IN