I've found a few thing's regarding sound in this build. With the same settings for my 5.1 speakers in Realtek's HD Audio Manager in both 8.1 & 10 set the same, 10 sounds a little bit louder. I've also noticed while listening to music in 10 with Windows Media Player, that the sound sometimes changes in how loud the sound is for a few seconds.
It appears to be a bug in the build itself.
Also, the Photos app crashes after a while while scanning my pc for pictures and if I click on restart it frequenly freezes.
So far, I don't really see 10 being fully usable when Microsoft releases it.