How to send the audio signal to two monitors via two HDMI cables?

English Hardware
1

I have two monitors with speakers connected to an amd graphics card using HDMI. Unfortunately, I can play the sound through one or the other monitor. Is it possible to send an audio signal to both monitors at the same time?

2

@alleran:

Which Desktop GUI are you using?

  • KDE or, GNOME or, something else?
3 
kde4-config -v  
kded5 5.71.0 

pacmd list-sinks | grep -e 'name:' -e 'alsa.device ' -e 'alsa.subdevice '
        name: <combined>
        name: <alsa_output.pci-0000_2b_00.1.hdmi-stereo>
                alsa.subdevice = "0"
                alsa.device = "3"

after switching to the second monitor

pacmd list-sinks | grep -e 'name:' -e 'alsa.device ' -e 'alsa.subdevice '
        name: <combined>
        name: <alsa_output.pci-0000_2b_00.1.hdmi-stereo-extra1>
                alsa.subdevice = "0"
                alsa.device = "7"
4

@alleran:

Actually, your KDE Plasma version seems to be …


 > kded5 -v
kded5 5.71.0
 > 
 > kf5-config -v
Qt: 5.12.7
KDE Frameworks: 5.71.0
kf5-config: 1.0
 > 
 > plasmashell -v
plasmashell 5.18.6
 >

Open the settings of the volume control Plasmoid – right click on the Loudspeaker icon in the System Tray – <https://docs.kde.org/stable5/en/kde-workspace/plasma-desktop/using-kapp.html#default-plasma-desktop> – or, use the KDE Plasma System Settings → Hardware → Audio …

  • In the Audio settings – the “Advanced” tab – there’s a check box for “Add virtual output device for simultaneous output on all local sound cards” …
  • Hopefully, there’s a generic HD-Audio profile for each HDMI cable …

If there isn’t, we’ll have to dig deeper …

5

Yes you can.

You have to install paprefs
Using paprefs under simultaneous output, enable add virtual output for simultaneous output on all local sound cards.

After doing the above you will have the simultaneous option in pavucontrol.

This is the easiest way IMHO in playing simultaneous sound from multiple audios.

6

I found a solution.

In the file:
/etc/pulse/default.pa

After the .fail line I added an entry:

.fail
load-module module-alsa-sink device=hw:0,7 sink_name=hdmi
load-module module-alsa-sink device=hw:0,3 sink_name=hdmi2
load-module module-combine-sink sink_name=combined slaves=hdmi,hdmi2
set-default-sink hdmi-combined

I read the numbers 0, 7 and 0, 3 after the command:

pacmd list-sinks | grep -e 'name:' -e 'alsa.device ' -e 'alsa.subdevice '

by switching the sound output on the plasma sound panel.