Qualified Krell service engineers have not been able to explain to me how it can work.
In my opinion they could not explain how it works because they knew it was marketing baloney.
Example of marking baloney in audio see below:
This feature plateau biasing circuit allows for the Krell FPB 600 amplifier to have Class A bias output without all the wasted electricity and heat. Really?
This is all very unsatisfactory and in the result I continue to use my KRS200s.
I agree, keep the Krell KRS200s if want new ''real'' class A amps see Pass XS300 mono block amps, they will give you all the heat you need to keep your English castle warm. 😎
Mike
https://www.passlabs.com/product_tags/class-a/