Best sounding DIY modules currently available.

Krell models, their imitators and DIY clones are, technically speaking, class A but use several sophisticated forms of sliding/switching bias to do so with much less heat dissipatation.

I am rather surprised with your comment. The only Krells that have been widely cloned are the KSA50/100, neither of which have any bias trickery.

Not sure i ever heard of a sliding bias model being cloned, although someone, somewhere must have done it.