I am on macOS. Most applications are able to accept changes to the audio device from the system and output sound to that device.
I use QEMU, and if I leave spice extensions disabled, the guest OS is able to accept changes to the audio device multiple times. When I turn on spice extensions, QEMU will try to continue outputting sound to the original device. No matter what I change the output device to, it will keep whatever it had originally. I don't know if it is QEMU using spice incorrectly, a misconfiguration, or a bug in one of the spice packages.
Oh, I have tried with a Debian bullseye and Whonix guest with the same results.
Has anyone found a workaround? Should I file a bug, and if so where?