Please setup bluez-alsa first and connect to your device, i will put instructions here in the future.
bjam <device address> <hw card device>
specify your device and alsaloop virtual device (on my system is '1,1', default hardcoded). Put your favourite player (browsers too except firefox, I use palemoon) and enjoy. Note, after stopping bjam, you may need to reload the browser (if you were listening audio).
bmicjam <device address> <hw card device>
specify your device and alsaloop virtual device (on my system is '0,0', default hardcoded). Enjoy your bluetooth speaker as an amplifier.