Are small cooling fans recommended for HT equipment that may heat up quite a bit?? I just built an equipment rack, and I want to be sure my equipment won't overheat. I have about 4" of free space above both my amp and my receiver. (equipment on other shelves will obviously not heat as much, but still have plenty of air space) The entire rack is placed in a corner of the room. (Two faces are completely open to room, one face directly against a wall, one face has 10" breathing room) Should I get a small fan?? If so, where can I get one designed for this??