Class A amplifiers - which are considered the best

@Sidekick I do agree the Karans do sound good but their claims for 470W Class A in that chassis that's comparable in size to the Krell 25W mono blocks seems odd, don't you think?

Krells are great amps, just that we were mislead quite a bit by many manufactures even today about Class A.

eg: Zaphod1000 said he once measure Musical Fidelity's little A1 integrated (you know the one, you wanted to wipe your feet on it)in spec, at 2 odd watts class A, they quoted 20watts!!
And their big daddy of yester year the A370 at 12 watts, they quoted 185watts!!.

Cheers George

@Doggiehowser

The construction of the Karans are obviously different to a "traditional" Class-A design, as explained below(source: http://www.6moons.com/audioreviews/asi4/3.html):

"All Karan power amplifiers are characterized by a continuous sliding bias control. This is unlike the sliding bias used by Krell. Krell raised and lowered bias in predetermined steps like Mayan pyramids. In Karan designs an electronic circuit measures the incoming signal’s amplitude. If there's need for additional output power, the current on the power rails which supply the class A output transistors is raised instantaneously. When the input amplitude goes down again, the bias follows suit. This way the output transistors always obtain the right amount of current and the operational temperature of this hugely powerful class A amplifier remains luke warm even when driven very hard."

I can't tell how this might influence the character of the sound, but it seems like a very clever design with the benefits of less power consumption, (much)less heat and the possibility of a more compact(well...:) enclosure.

Didn't Nelson Pass create the sliding bias thingamabob?
:)

So does this sliding bias affect what George was talking about earlier when he said there was no way amplifiers could do 100s of watts of power in Class A mode?

I remember being approached by someone in the early 90s that held a patent to a sliding class A bias system (for transistors). As innovative as he is, I don't think Nelson created that. As I recall, it showed up on the Krell amps first.

We didn't go for it because our amps are tube. But I have thought about a tube-implemented class A system over the years. It might cool our amps off a bit!