I recently upgraded my existing AVR to Marantz SR7013. With 30 minutes of usage and running the volume level at reference -15dB, it was running hot. I have been using a laptop cooling pad which reduces the heat to an extent.
I have a 5 channel ROTEL power amplifier which I connected to the AVR after a week from the AVR purchase date. After taking all the front 5 channels (LCR + FHR & FHL) in my 5.1.4 setup to power amplifier, the heat has come down and there is a difference in the AVR temperature as the AVR front 5 channels amplification has been offloaded to the separates.
I have one more 2 channel power amplifier from KENWOOD to drive the remaining rear height channels. It not only improves the sound quality, it further contributes to take the excess heat from the AVR. Remaining 2 (surrounds) out of 9 channels are driven by the AVR itself. The heat produced for driving these 2 channels is negligible.
I am getting a AC Infinity Aircom T10 front exhaust fan in the coming weeks. I should supersede the laptop cooler better in sucking out the heat from the AVR. Cant really help for the heat produced by Marantz (Pretty much the same case with the other brand AVRs which drive 9 and more channels), no matter how many minutes / hours you use.
As much as possible, keep the AVR and other equipment ventilated and have them run in air conditioned environment. If not possible, at least have the ceiling fan ON. A laptop cooler or a proper AVR cooling systems like AC Infinity Aircom products would help in reducing the heat to an extent for sure.
Fully agree with you Mr. Sriram. Powering them by separates would further reduce the load on Marantz but not sure if it is an option for many people. The Marantz gets very hot. The AC Infinity Aircom is a good option. Even I was facing the same dilemma when I got the Marantz SR 7011. It used to get very hot barely after approx an hour's usage for stereo listening considering that the top of the receiver was open & there was nothing on top of it. I had to install an AC just to keep the Receiver cool. I had asked a technician once regarding this issue & he told me that the HDMI board gets hot, not sure if this is the only cause. With movies it gets even hotter. After keeping the ECO mode on Auto it reduced the heating drastically in my case.
Prior to the 7011, I had the Marantz SR 8200 which was a 6.1 receiver. After using it for approx 5 hours continuously at moderate volume it would get barely warm & generally run very cool & its heat sink fan never ever came on in its 10 years of usage . It did not have any HDMI connections.