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 ?


My Pass Aleph 1.2 monos are pure class A, no pull stage. 200W at 8ohms / 300W at 4ohms.

The Nelson Pass Stasis patent also incorporates a sliding bias voltage to increase the efficiency of an amplifier run in class A.  He used it in many of the Threshold amps and also licensed it to Nakamichi.

I’m curious about the D’Agostino Relentless Epic 1600, is that a pure Class A?