• First Response:
  

Explain to this asshole that you need your "Beauty Sleep", and if you are deprived of this by their early morning "concerts", you will indeed get "ugly" with them. State this in a way that implies serious physical harm.


• Second Response:
  

If this repulsive behaviour continues, you are free to assume that physical harm is not a deterrent. This leaves you no alternative but to neutralise the offending stereo. You need some straight pins and a pair of wire cutters. Remove the grille from the front of both of the speakers. Push a pin through the cone at the edge of the voice coil, into the magnet gap that the voice coil moves in. Clip off the head of the pin with the wire cutters, and nudge the pin all the way in until it is no longer visible. It may take a minute or two for this cretin to realise that all is not well, but the resulting damage can range from crunchy bass to fried amp and/or speakers.

Either way, "Another One Bites The Dust"!

.. or you could simply deck the S.O.B. and leave it at that ...

...{afterthoughts}...

• schmange has some interesting ideas... depending on the laws concerning involountary psychiatric observation in your locale, they might lead to unhappy conclusions.
  


• There is always the possibility of a more powerful stereo replacing the original offender. But then, pins are a lot cheaper than stereos!
  


• Since the people that come to visit him end up spending so much time with you instead, you have an uparallelled oportunity to alienate these people from him. No falsehood required - his obvious absence should be enough.
  


• You have guitar and an amp? Since you're awake anyway, reply to the outbursts from "Der Roomie" with as many dB of SPL as you can provide! Scales, riffs, whatever you feel like playing.
  

After all, if reasonbale discussion (you did try that. didn't you?) fails, there is only [u]un[/u]reasonable reaction left to you!