Hello Anonymous
No, unfortunately that doesn't work with the Sennheiser either, at least not in BT mode.
At best in cable mode (it can also be operated uncharged / switched off), but I haven't tried that yet and it's certainly not the solution you're looking for.

No, can be set to minimum with the app. I had reservations, but in the end I accepted it when using it because it wasn't annoying. The most negative point is that certain older Bluetooth devices cannot be paired (e.g. old Sennheiser Bluetooth transmitters!)