You need to get a written complaint signed by all your other neighbours and take that down to the police. From there on out, every time he plays that bass so loud, just call the police. Each time a call is made, make sure it comes from a different person on the list. That way you don't become a nuisance to the police. The common factor/nuisance then becomes the dude with the bass. They will sort him out.
If that doesn't work you have to move I'm afraid.
