Poor quality audio
I used audioctl to get the maximum possible volume the driver allowed but it's still very low compared to FreeBSD and Linux. The sound quality is not good but acceptable, except the noise of it. Listening to an arbitrary MV on youtube, it usually have noise randomly inserted into the audio for a short time but it appeared many time through out the play back. I know it's poor quality audio stack caused this because I observed the same on NetBSD, except NetBSD is somewhat better than OI.
I also think the choice of your to PulseAudio is problematic. PulseAudio sucks and it prevented the system shutdown for numerous time. A commonly used trick of mine is to shutdown using sudo poweroff but not the MATE menu because it could bypass PulseAudio. To be able to shutdown with the MATE menu, I have to kill PulseAudio first with pulseaudio --kill before try to shutdown. It's annoying!
On the major BSDs, none of them used PulseAudio at all. Pulse is available as a package, but they rather deal with ALSA than Pulse. But ALSA is missing on OI! My Firefox on BSDs is powered by either ALSA or SNDIO, not Pulse! As OI already porting numerous drivers from the BSDs, I think sound drivers are not exception, why don't just do the same as the BSDs? Why have to stick with that awful PulseAudio at all?