Comment 9 for bug 319281

I just tested karmik alpha-5.

The sound preferences dialog has a hardware "tab". There is an option:

"Settings for the selected device"

where the profile can be choosed. There are options for many the output devices. Among them:

"Analog Surround 7.1 Output + Digital Stereo (IEC958)"
"Digital Stereo (HDMI) Output"
"Digital Stereo Duplex (IEC958)"
"Digitial Stereo (IEC958) Output + Digital Stereo (IEC958) Input"
I attach a capture from the dialog.

I think the IEC958 should be Surround 7.1, I tried speaker-test and it fails for more than 2 channels:

"Digital Surround 7.1 (IEC958 7.1) Output"

aplay -L
front:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    Front speakers
surround40:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Intel,DEV=0
    HDA Intel, ALC888 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Intel,DEV=0
    HDA Intel, ALC888 Digital
    IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=Intel,DEV=0
    HDA Intel, INTEL HDMI
    HDMI Audio Output

$ speaker-test -Diec958 -c3 -twav

speaker-test 1.0.20

Playback device is iec958
Stream parameters are 48000Hz, S16_LE, 3 channels
WAV file(s)
Channels count (3) not available for playbacks: Invalid argument
Setting of hwparams failed: Invalid argument