Class A amplifiers - which are considered the best

Love to see that brochure. In any event, they sure fooled me. Still thought they were great sounding amps. I couldn't get past the sound of those fans on their predecessors.

Goerge, Krell had some Class A amps sans fans before Plateau Biasing, yes, with copious heat sinks. Still amongst my favorites.

I was referring to the Krell KSA 80, KSA 200, KMA 160, KMA 400s.

Goergelofif, the Krell KSA 80 and KSA 200 (and their mono counterparts the KMA 160's and KMA 400's) preceded the KSA 250 by a couple of years and were of different design generations.
http://www.krellonline.com/history.html

Georgelofi, I did see your link. I believe that at the time Mark Levinson was building those amps, he was charting fairly new territory, and those amps were overbuilt. Compare the size, weight & number of chassis, to a newer Class A amp capable of similar Class A power output:

http://www.stereophile.com/content/pass-labs-xa305-power-amplifier-specifications

I think your overall point is well taken though. Some, if not many amps that suggest pure Class A output, are questionable in that regard.. The Aragon monos, the BEL's and some of the Electrocompaniet amplifiers amongst others, do appear to be stretching credibility with their Class A claims.