I have had similar thoughts with my system. My rack is pretty much fully enclosed and built into my wall, so stability is not an issue. I'm getting ready to put some exhaust fans into it to provide some air flow to keep things cool. As it stands now, the shelves are pull out shelves with 100 lbs. capacity. So when I'm using my hot running PS3, I slide that shelf out to have it in the open air. I've thought about placing my amp on the top of my rack, but I worry that it could run too hot up there even with the exhaust fans.

Any thoughts? How cool does the amp need to be?