no simultanious audio to built in and HDMI

I can have audio only on either built in speakers OR HDMI.
(OS 15.3, KDE / plasma)

in plasma -> system settings -> hardware -> audio -> advanced I activated “virtual outpput device for all local souncards”
available output options are then
“Internal audio analog stereo” and
“simultaneaous output to Internal audio analog stereo”
Having a simultaneous output to the same device doesn’t make sense to me.
(same if HDMI is selected as output: then the simultaneous output is as well HDMI)

how can I have audio on both built in speakers as well as on HDMI?

… interesting:
when adding a bluetooth headset, then I can have simultaneous audio output to the headset and to EITHER HDMI or built in, but still no simultaneous output between HDMI and buit in

In pipewire it is not possible.
If you are using pulseaudio it is possible by installing paprefs.
Enable simultaneous sound in paprefs.

as you can see from my posts, simultaneous sounds is already activated. I set it via pavucontrol.
the problem is that no all sound devices can be simultaneous, ie. HDMI can not be simultaneous with the built in analog audio of the laptop.

When you said pavucontrol. You activated the simultaneous sound using “paprefs” right?

I activated to add a virtual output device for all local sound cards in KDE/plasma system settings.
in paprefs it was therefore already activated.
in (eg.) pavucontrol I select the simultaneous output that is available

I’m sorry about that. I don’t have the Leap 15.3 to try.
I am using tumbleweed with pulseaudio and the simultaneous output is
perfectly working here. I am using xfce and I use the pavucontrol for my audio.