Check your noise ordinances, for DB levels and times in effect. If there's no law, first ask him if he's deaf, Then offer a nice set of earbuds and a personal player. If not receptive,
Speakers should be cheap at a pawn shop. And a crappy amp that barely drives the speakers. And a cheap tuner to get the religious music station, the more "contemporary Christian" the better. That stuff is objectively A W F U L.
