You're just looking for 2 channel stereo? Or do you want to work your way up to full 5.1 (7.1) Home Theatre? The room is 20x20, but how far away would you be sitting while listening?

If you have $1500 to spend, and are just looking for 2
channel stereo, and can sit at least 10' back, I'd recommend this...

Axiom M60ti $800
Rotel RA-1060 (integrated amp) $700

That would sound sweeeeet.