Recently I got a very nice bluetooth speaker from Bose. When I paired it with my smartphone, the sound quality was much better than when paired with my laptop. It turns out, my laptop was for some reason picking HSP/HFP profile instead of more advanced A2DP.
I changed this setting, but after each reconnect it was disregarded.
The simplest fix is to make Ubuntu ignore HSP by adding this line to [General] section of /etc/bluetooth/audio.conf:
and then restart bluetoothd
service bluetooth restart