While I do not understand their magic, this guy does all class A only, I believe his theory is, "if the first watt sucks, why continue". His go up and down from 8ohm to 4ohm, in either direction. All I know is, the stuff sounds pretty awesome. While I don't go to magic shows, their stuff is pretty magical.
CLASS A POWER RATINGS
In well designed SS class A power amps I was told that although power could increase to double in class AB mode from speaker demands of 8 ohms to 4 ohms, class A suffered to be cut in half.
For example a class A denominated amp rated at 50 watts class A into 8 ohms would double to 100 watts class AB into a 4 ohm load but only have 25 watts of class A power before switching to class AB.
But I've noticed of late claims of manufacturers stating their amps double their class A power as impedance demands are halved.
So is the explanation that technology has advanced ?