PulseAudio depends on a dbus system daemon, make sure its enabled.

# xbps-install -S alsa-utils pulseaudio
# ln -s /etc/sv/dbus /var/service/

The PulseAudio package comes with a services file, which is not necessary in most setups and its discouraged by the PulseAudio maintainers to use the system wide setup.

There are different methods that work with PulseAudio to allow access to the audio devices, the simplest one is to just the audio group alternatively you can use a session manager, like elogind or ConsoleKit2.