Meta Quest 3: No Sound via Headset nor via Streaming Speakers

[Crossing Gamer]

The Sound does work though. But only if I route it manually over my standard Audio Output to my Hifi. When I try routing it automatically to Headset or manually to Streaming Speakers, my Quest makes no single sound. And it is not the Quest itself. When I navigate in Quest OS I hear everything.
Where is the problem here. I also already have reinstalled the drivers for the streaming speakers and reinstalled whole steamVR. I killed the .vrsettings for a reinstall and also recoupled the headset itself. Nothing works..... Anybody ideas? I heard, that I am not the first one to whom that happens....