I pull conditioned air through our equipment rack and exit it through a return air vent that ducts straight to the house a/c return air system ... I did that because the room is pretty much sealed tight and we used outside doors so that we could try to contain the sound as much as possible from the rest of the house, and the use of a couple of PC cooling fans on the AVR and amp helps keeps those particular components cool.
No concerns about pulling the heat back into the system in the summer? Or do you have a by-pass? or shut off?
My unit and duct work are basically above and to the side of the rack. so tying into existing ducts is easy.