Created attachment 177214 [details]
Output of $ alsa-info.sh

SUMMARY
The Audio Volume (AV) widget causes stuttering sound (and/or video) and a crash of pipewire. This happens either if the AV widget is opened, re-opened, or closed by clicking on the AV icon (speaker). Thereafter, pipewire has to be restarted (which may take up to ~ 20 seconds):
   $ systemctl --user restart pipewire

When moving the mouse pointer over the AV icon (speaker), the volume can be changed with the mouse wheel without any problem. The same is true when changing the volume with keyboard shortcuts.

I'm not sure if it is a problem of the AV widget, of alsa , or of the apple_bce module of the kernel 6.12.1-arch1-Watanare-T2-1-t2 (64-bit), which is required to get any sound on this machine.

STEPS TO REPRODUCE
1. Play video in browser or play audio
2. Open the Audio Volume widget (plasma-pa) by clicking on the AV icon (speaker)
3. Close the AV widget or re-open the closed widget by clicking on the AV icon (speaker)

OBSERVED RESULT
During 2. or 3. the sound (or video with sound) starts stuttering. Lots of crash dumps are logged.

EXPECTED RESULT
No stuttering is observed.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.9.0
Qt Version: 6.8.1
Kernel Version: 6.12.1-arch1-Watanare-T2-1-t2 (64-bit)
Graphics Platform: Wayland
Manufacturer: Apple Inc.
Product Name: iMacPro1,1

ADDITIONAL INFORMATION
kmix has been uninstalled.
Active audio device in AV widget: card 0: Audio [Apple T2 Audio], device 0: Speaker [Speaker].
$ lspci | grep -i audio
02:00.3 Multimedia audio controller: Apple Inc. Apple Audio Device (rev 01)
f3:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Vega 10 HDMI Audio [Radeon Vega 56/64]

Attachments:
1. Output of $ alsa-info.sh
2. Output of $ journalctl -b | grep -v bluetoothd | grep "alsa\|pipewire\|kernel\|sound\|snd\|bce"