You need some packages first

sudo xbps-install libpulseaudio bluez-alsa

Now make some changes in bluez-alsa service /etc/sv/bluez-alsa/run to add support for A2DP support:

#!/bin/sh
[ -r ./conf ] && . ./conf

install -d -m0755 -o _bluez_alsa -g audio /run/bluealsa
exec chpst -u _bluez_alsa:audio bluealsa -p a2dp-source -p a2dp-sink
#exec chpst -u _bluez_alsa:audio bluealsa $OPTS

then start it

sudo ln -s /etc/sv/bluez-alsa /var/service

sudo sv start bluez-alsa

Make sure to stop alsa service first. sudo sv stop alsa. You pulseaudio should be restarted.