Use line-in jack for 7.1 surround

Question

I follow the instruction in this question: How to split 7.1 soundcard outputs to 4 stereo outs with ALSA

I am able to use the first three "channels" for my multiroom system.

However the last one did not work. (segmentation fault when I try aplay)

My sound card is the embedded one on the Asus ASROCK J4105ITX

According to the documentation for a 7.1 surround sound output the line in has to be "converted" to a output.

Can I do that through the asound.conf file? (May be my bindings numbers are not the correct one)

Bindings: 0 1 are the green connector (front speakers)

2 3 are the black connector (rear speakers)

4 5 are the pink connector (microphone!!!!!!!)

6 7 are not working (connector ???????)

I was expecting to use the Orange connector (center/bass speaker) and the line in (light blue) connector instead of the microphone

Thank you

Answer 1

install alsa-tools-gui

then run one of the ALSA tools in that package hdajackretask

enable option 'Advanced override' to make settings visible

find section for 'Blue Line in'
enable option 'Override'
change setting for 'Device' to 'Speaker'
change setting for 'channel' to match other Speaker

click 'Apply now' to make temporary reconfiguration of ALSA (changes will be lost if pc rebooted)

Open alsamixer and check if a level control for missing 2 channels (side?) is now present (controls for line-in should not be present)
unmute and adjust level settings, if required

if all channels for surround sound are confirmed to work
click 'Install boot override' to make reconfiguration permanent (changes will be lost if pc rebooted) and save new settings for ALSA

sudo alsactl store

reboot and check audio still works