If heat is a serious problem, as well as the potential need for much higher peak output current capability, you might want to run class D power amplifiers in the summer months. There is a pretty good selection of them now with at least decent sound, most at pretty affordable prices compared to the top rung class A or AB amps you are considering. When the weather turns cold, switch over to your high-power class A or AB amps and let them help you heat the house. I used variations of this scheme for many years and was quite happy with it. Just a quick alternative idea to consider - good luck finding a satisfactory compromise!
