@KEW - I think it depends on if you are using ECO mode. I was running ECO mode as my 4500 and 4700 were running hot after a short session. ECO reduced heat but also cut amp power by 50%. I can hear the difference between using the Denon in ECO mode vs using the Monolith 7X external amp at moderate listening levels (70db+).
I purchased the
AC Infinity AIRCOM T10 to fight the heat issue but I could hear it's fans even at the lowest setting so I returned it. I'm going to try the
AC Infinity MULTIFAN S7 and see if it offers less noise.
Until Denon provides better cooling across its receiver line I see why an external amp might be a viable option for reducing heat. If you don't care about how hot the receiver gets then turn ECO OFF and use the internal amps. OR maybe you can find a fan setup that doesn't distract from the music/movie?
Certainly if you have ECO in the on position and your speakers or listening levels are demanding, you could be running out of available juice. I wish Denon had incorporated an indicator to show if/when the power is being limited by the ECO setting! Of course you can listen for the click, if in the "Auto" position, but given the wide range of experience their customers have, I think it is a mistake to have an option to F up the sound (without a notification). Between this and the 4 vs 8 ohm switches on some units, it almost seems like AVR manufacturers want you to screw up the sound!
Of course, we are all a little different, but the S7 was the ticket for me! I suspect that the T10 is probably the loudest option with the exhaust pointed at you (not that it is "loud"). I have the rear-facing version of the T10. It was pretty quiet, but once in a blue moon, the sound of the fans turning on was a distraction. While I love the idea/sophistication of the thermostatic control system, I find the S7 set on low (always, as just a dumb fan) keeps my Denon cool and is never a distraction! I wish I could tell you that I absolutely cannot hear it, but when it is quiet at night and I make the effort to listen for it, it is audible. At the time I got/tested it, I decided that I would have to keep looking for the "perfect" solution, but at $20 I would keep it in play until the time I found a better solution. That was over 2 years ago and I am no longer looking for a better solution. What I have found is that, for me, the S7 is
never a distraction. Typically, I cannot hear it if I listen for it because there is normally HVAC, refrigerator, air filter, or some other noise in my house that is not so quiet (although they are all quiet units). More importantly, it was the noise of the "start-up" of the fans that caused the thermostatic unit to be a distraction.
YMMV, but let us know how it works out for you!
