Add support for Bluetooth Low Energy
A2DP devices using BT LE (like the whole range of BOSE Soundlink speakers) are unsupported right now in Linux.
Volume is blocked at ~ 10% and no way to set it higher, even with physical buttons (on BOSE Soundlink). Imho these devices expect Volume to be set "on the speaker" through BT (AVRCP ?), not set on the source.
Note 1 : result was the same with Pulseaudio
Note 2 : it works very well from any Android tablet or smartphone