Onkyos do not run hot, I've owned two of them. They run warm just like every other receiver on the market. I suppose if you stuffed it in a cabinet w/no ventilation that it would run hot but so would any other receiver.
I don't know who started this "Onkyo's run hot" stuff but it's wrong. By the way that panisonic xr45 would crossover at 100hz, kind of high for the speakers you plan to use. Anything over 80hz is localized and your sub, depending on size, may have trouble at the higher frequencies.
