If I’m running Qubes OS and I plug headphones into an audio jack on my motherboard, which Qubes can access my headphones?
If you don’t have sys-audio set up, I think it gets handled by dom0, as that’s where the audio system lives by default.
I’m wondering whether someone who hacks into a qube that is connected to the internet can access my speakers (and then potentially use them as a microphone).
It is possible to use a speaker as a microphone because the hardware is very similar.
I believe that should not be possible, as Qubes only see virtual audio devices that should implement only one-way communication.