Unable to change volume on second pair of internal speakers - 19.10 - ASUS ZenBook 14 UM431DA

Question

I've recently instaled Ubuntu 18.04.4 LTS, then 19.10 and finally I updated to 20.04 beta (currently 19.10). I've incouneter same issue on all of them.

This laptop has harman/kardon quad speakers and if I change volume it affects only 1st pair (Tweeters), but 2nd pair (Woofers) is always on full volume, until sound is fully muted. Sound chip is Realtek ALC294.

what I've tried: changing audio configuration in audio settings to 2.1 and 4.0. In 2.1 mode bass speakers didn't made any sound. Upgrading OS version. Fiddling in alsamixer (found out Bass Speaker volume is "00" and cannot be changed). Everything works fine on headphones.

/proc/asound/cards:

0 [Generic        ]: HDA-Intel - HD-Audio Generic
                     HD-Audio Generic at 0xfe7c8000 irq 72
1 [Generic_1      ]: HDA-Intel - HD-Audio Generic
                     HD-Audio Generic at 0xfe7c0000 irq 73

$ pactl list short sinks:

2   alsa_output.pci-0000_03_00.6.analog-stereo  module-alsa-card.c  s16le 2k 44100Hz    RUNNING

$ aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: Generic [HD-Audio Generic], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Generic_1 [HD-Audio Generic], device 0: ALC294 Analog [ALC294 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

Many thanks to anyone that is able to help with this!

Answer 1

I noticed that tough alsamixer Master volume don't change bass volume, PCM does. So maybe following this solution may help. It helped me. Just in case something happens to that link here are the steps:

I edited the file /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf.common (with sudo).

I added the following lines before the [Element PCM] block:

[Element Master]
switch = mute
volume = ignore

The file should look something like this, with the new block first:

[Element Master]
switch = mute
volume = ignore
[Element PCM]
switch = mute
volume = merge
override-map.1 = all
override-map.2 = all-left,all-right

and run in terminal:

pulseaudio -k