“hey man what’s going on, sorry to bother you but there was a bit of noise that I think was coming from yours last night and normally it wouldn’t bother us but it was fairly late and stopped us sleeping, would it be possible to turn it down next time just a little bit if that’s okay”
Then if you want to be chill with them even more the next time they play music but it’s not as loud or distributing go round the next day with a couple of beers or a bottle of wine for them as a thanks