Just installed Sennheiser MB Pro 2 UC Bluetooth wireless headset and cannot hear sounds but can hear via desktop speakers (Bose).
The Volume Mixer for Device shows:
Speakers (Realtek High Definition Audio)
Headset Earphone (2 Sennheiser BTD 800 USB)

If choose Speaker, sounds are good (i.e. can hear them) but if choose Headset nothing !

The Headset is used for Dragon NaturallySpeaking and the microphone works fine.

Sennheiser messages (i.e. Power on and Talk Time) can be heard okay.