My AVR sets on the lower shelf with 6" of open air space above it and 2 1/2"
on each side. I purchased two 6" plastic fans with the spring clamps on the end and cut open the back of my cabinet and have the fans blowing across the top of the AVR(from the rear) and have plugged into back of AVR. If AVR is on fan is on. I have a second fan and moved it to blow behind the Revox R2R that sets on top of cabinet. It is a mess of wires behind the cabinet/fatt screen stand. DVD, Bluray and CD players, R2R and Verizon Fios 2 subs and 5 pairs of speaker wires.Wii and Yamaha Ipod docking station........gives me a head ache.
I was talking about extra "Head Room" in the amp sections...reserve of power not being used when watching Blurays.