You could knock on his door, introduce yourself in a friendly manner, and tell him that you know that since he is new he didn't understand how his stereo bass is thumping through the building. You could approach this with him as you are offering to help all of you out, everyone can work together to make the environment comfortable for all. Maybe he will even work with you on figuring out where he needs to set his stereo properly.

I've had to deal with soooooooooo much noise over the years, so I know what is like to be in your shoes. Some neighbors can be real horrid. When you ask him to turn the noise down you aren't doing anything wrong, you aren't starting a fight, even if he or others try to make you feel that way. This is his choice, in other words if he acts all pissy, that is not your fault.

I think it is fine to talk with him now rather than wait to see if he will get a clue on his own.