You can't just put any music you want into the game, it's simply not within SA-MP's current limits.
The only possibility is to put in some certain small "sounds" which are not really considered music. The full sound list that could possibly be added is available on the SA-MP official wiki. Please consult with it. It's the only possible sounds that could be played in a house.
Therefore it's not really possible, the sounds available simply wouldn't be good enough for this to be worth it. I'm sure there's even an in-game music player to try these available sounds out, with /music on or off.