Shadorne, I hadn't thought about the amps in ATCs that much. If they run Class A... does the speaker enclosure throw off a lot of heat?
A fair amount (as much when they are idle as when you run them hard) but remember that the amplifier does not have to power a lossy passive crossover or handle large impedance swings - since it is band limited to only the frequencies necessary for the particular driver. This allows for much greater efficiency and optimization.