Interesting post Bigjohn. My onkyo runs hot as well. My old Onkyo that I had for just under 10 years ran hot as well. In fact the friend I sold it too has it in a small cabinet and had it melted the feet of his dvd player that was placed on top of it. (house cleaner closed the cabinet while listening to music and cleaning the house, the cabinet went thermonuclear).
I have considered the fan idea but worry that the noise would be pronounced although probably no more than my dvd player making noise while spinning the little discs. Definitely let us know how it goes if you install the fan.
I have run my newer 601 for hours and hours and it does get pretty scary hot but so did the old one and its still kicking after a decade of heat.
