I always recommend this if you have a place for the air to exhaust to! I run mine on low whenever my AVR is on and I never notice them, but my Denon 4400 AVR stays cool (only slightly warmer than room temp)!
If the space in your cabinet is not well ventilated, or if the AVR is too close to the shelf above it, then one of the front or rear exhaust versions of these is best:
I would prefer the rear exhaust as the front exhaust is more likely to be audible, but if your only ventilation is out the front that is the one to get. Not that the front or rear Aircom units essentially place a slelf immediately above these fans, so if you have extra height clearance, you can put hockey pucks under the feet to allow very easy airflow into the bottom of the AVR!
If your cabinet has a door or you just want to supplement, one of these is useful to ventilate the cabinet (marginally as a stand alone, but in addition to one of the above you've got no heat issues):
Other comments on these:
1) Several of these have the option of a thermostatic control (designated by a T as in T8). This is what I have and if I was doing it over, I would
not get the thermostat! Not only will you save money, but anytime the thermostat kicks the fan on (when the sound is quiet), I notice the fan starting up. I assume the fan pulls more power and is louder during start-up. Once it is running steady at low speed, it is quiet. Of course the thermostat is also more likely to be a failure point.
2) Where possible, use a two (or three) fan unit. That way were a fan to fail, you would not lose all ventilation and hopefully you would notice before the second one failed (although most modern electronics are pretty graceful with their thermal overload switch) and could replace the unit. Happily most of the failure include annoying noises that would get your attention (these are essentially PC fans which you may have heard when a bearing is going bad or dust is causing interference).
3) If you have an enclosed cabinet, put the Airplate up high (heat rises) as an exhaust fan to pull hot air out. If you ever lived in a house with an attic fan in use you will appreciate this easier, but you need to think about where you are drawing air from and how it will flow through the cabinet to the fan. You want to encourage it to flow
through you AVR (and other electronics that generate heat). Often, this may mean pulling a shelf out and drilling holes (match their location to the vent holes in the bottom of your AVR) and you may also need to seal a gap at the back of the shelf (Home Depot has lots of foam strips, etc similar to how you would seal a window fan or AC).
If you do need to drill holes in the shelf, use a 3/4" hole saw (like the image below $10 at Lowes.com). The reason I am specifying a hole saw like this is you will end up with cleaner holes. With most drill bits, you will end up with a mess when the bit exits the back side of the shelf (especially with some of the laminate finishes being used). With the hole saw, drill from one side until the center bit sticks out the back side (do not push hard, let the tool cut, I would try it on a piece of scrap wood if you are a hole saw virgin - maybe apply three pounds of force behind the tool), then, simply stick the bit in the hole and finish cutting the hole from the back side. That way you never have the tear out from the saw actually exiting through the finished surface!
I would leave 1/2" between holes just to make sure you do not reduce the strength of the shelf. Also keep all holes inside the rectangle you would have if you drew lines inside the feet of your AVR. As long as you stay inside the feet, the shelf does not see much load anyway!
