In my previous post about

installing Sandberg USB Sound Box 7.1 on Linux Rune K. asked if digital input through S/PDIF line in port works on Linux. Yes, it nicely does, but as usual, configuration has to be tweaked.

First, don’t alter PulseAudio Volume Control settings – I had „Analog Surround 5.1 Output + Analog Stereo Input“ selected for my USB sound card. Let it be as it is:

Sandberg USB Sound Box 7.1 settings in PulseAudio

What you need to tweak is AlsaMixer – run in Terminal:

sudo alsamixer

And hit F6 to select your sound card – in my case it’s „USB Sound device“. Use right arrow to select „PCM Capture“ and by Up/Down keys pick „IEC958 In“:

Enable digital auio input using AlsaMixer

Esc to close AlsaMixer.

In sound capture software like Audacity make sure to select:

  • Audio Host – ALSA
  • Input device (in my case) – USB Sound Device: Audio (hw:3,0): Line:0

Make sure audio is on from TOSLINK cable and try to record. I was successfull to record stereo stream (PCM 2.0) coming from my Samsung Smart TV:

Stereo sound recorded through S/PDIF on Audacity

I didn’t try to send Dolby 5.1 or DTS sound through TOSLINK, but I believe Sandberg USB Sound Box 7.1 supports stereo only through digital ports. When I bought the device I had hard time trying to output Dolby 5.1 through S/PDIF to home theatre system – all it was receiving was PCM 2.0, so I assume input is stereo-only as well.

Further reading:

Featured image source: Wikipedia – Some rights reserved.