Bluetooth A2DP - Ubuntu

Type in a terminal:

sudo apt purge pulseaudio-module-bluetooth bluetooth bluez-* bluez
sudo apt install blueman bluez pulseaudio-module-bluetooth
pactl load-module module-bluetooth-discover

 

Go to Blueman, connect to your device and set its audio profile to A2DP with high quality sound.
Go to Sound Preferences to select the headphones as your audio device.