But that is the nature of class A amplification, is it not? Considering that class A is only about 25% efficient and the 5802 is supposedly biased to operate as class A to around the first 50 watts, the idle consumption of 540w seems to make some sense.

Regarding the sound, I can say that the 5802 easily out performs the 545II, 555 and 555II. IMO, the improvement is so distinct that I would question the hearing of anyone who cannot tell the difference. Now I will admit that I am not sure if the difference is due to MOSFETs vs. Bi-polars, or class A vs. class A/B. I would love to listen to another of the Adcom MOSFET designs like the 5500 to try to better understand nuances of each design philosophy.