5.1 sound on Ubuntu 20.04 LTS with 3 3,5mm jacks allows stereo onlly
Solution 1:
Same problem here!
The answer below has just solved the problem. Now sound is coming from all 6 speakers!
https://askubuntu.com/a/767033/687814
A cowardly newbie, I didn't touch the /etc/pulse/daemon.conf file but just changed the number of channel to 6 in alsamixer on the terminal.
With a little courage, I've just tried default-sample-channels = 6 and erased the semicolon before the line as somebody instructed. Now I can see every speaker on the Settings. But the volume of the subwoofer isn't controlable. This shitty OS is eating my time and soul.