I had trouble getting sound in my Bose QC35 ii headphones connected by Bluetooth to my Macbook Pro 2015 running Mojave 10.14.6. After today, I don't get any sound at all.
The only way I get them to output any sound is to open System Preferences > Audio > Input and select the Bose as input. Then it plays, but it's noisy and sounds really bad. As soon I switch to another tab or close the window, after some seconds the audio output stops. The Bose is definitely selected as audio output device.
Internal sound and speakers connected to the line out are working fine.
What I have tried so far:
- update the firmware on the phones
- reset the headphones (following the Bose web page: switch off, wait, charge by USB, wait, switch on again)
- deinstall all unused audio drivers (Apowersoft device) and restart.
- disconnect all bluetooth devices and pair them again.
- SMC reset
- PRAM reset
- ALT-SHIFT click the Bluetooth symbol in the status bar DEBUG -> Reset Bluetooth Module & Remove all Devices and pair them again
- switch off BT and delete /Library/Preferences/com.apple.Bluetooth.plist* & ~/Library/Preferences/ByHost/com.apple.Bluetooth* files and reboot
- disconnect external Display Port monitor to get rid of the audio device.
Everything to no avail. I am really out of ideas and my google foo ends here.
The headphones are connected to my Windows 10 PC as well.