I used to have the SR4300, never had any problem with it even if it is just connected to a surge protector and not an avr. Once there was a fluctuation of electricity at our place while I'm listening. The SR4300 didn't even blink, it just sort of paused the sound then resumed normally. I usually have it set at -25db for my normal listening level, but the speaker levels were biased at 10db, for about 6 hours straight after office, everyday.
In comparison with my HK, the Marantz do become hotter, contrary to what I have expected with the HK being a high current amp.