I live in an upstairs apartment with my Set up. My room is 12 x 18, but the couch is forward in the room so the seating dimensions are more like 12 x 12. My system could be overkill, but I do not think so. If you can afford it go as big as you can, but make sure to ask the Axiom people whether or not the speakers will work in your room.

And my sub goes down to 25Hz, and I never get complaints from my neighbors (knock on wood).