My memory doesn't go back that far. But fortunately the site does. From my review:
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FYI I am in discussions with Denon/Marantz folks about thermal issues. They like to investigate what I have reported. I am asking them to lower the threshold for the fans to come on. Will see if they go for it.
Blowing dust in to the units, when the fans might not actually be required, is a good way to create thermal problems when none previously existed. Increasing the duty cycle of the fans adds a potential area for mechanical failure. Fans also add noise, which is undesirable. Dust covered fans add more noise. The use of fans to effectively cool electronics really should include filters for the air entering the unit and other engineering steps. It requires a systems approach.
The thermal and current protection systems in the Denon's, especially the higher level models, are quite extensive and clearly have been the subject of extensive engineering by Denon. If the thermal systems are poorly designed in isn't for a lack of trying or attention to the subject on Denon's part. The three year warranty period is long enough that Denon needs to get the thermal system "right" or warranty claims will be excessive.
There is a tendency to personify the temperatures found in electronics. AVR's aren't people! Don't be irrational about this.