Years ago, when I was learning electronics, transistors had taken over from valves. I remember my college lecturer talking about all the various classes and comparing them to cars. Fiat 500s, Citroen 2CVs, Rolls Royce - and comparing the 2 stroke, 4 stroke and 4, 6 and 8 cyclinder versions. Of course we all dismissed the low capacity small number of cylinder ones and looked at the V6 and V8 big designs - and his correlation to valve (tube) designs made perfect sense. Then he wrecked it by pointing to the big smoky bulldozers in the car park. His point was that clever engineering could make the 'worst' design the best, while the best engineering could also be terrible used in the wrong application.
Amplifier design constantly evolved as requirements changed. Class A, B, AB and the others all have the capability to do the job - the snag of course is price. Tubes and then solid state devices all relied on the spec sheet - showing what the limits were, and you designed products to do only what you needed. You could design in low distortion, higher powers, frequency response and lots of other features - but you rarely could have all of them.
There is an irony to musicians and technology. We're the only group who demand sonic coherence, so that we can then wreck it with another gizmo down the line.
Guitar amps are the best example - if you feed in a commercial track .wav file from a decent device and listen to the result - through built in or external speakers, nobody would ever think that was remotely hi fi.
That's why we'll never agree - all the flaws in the designs that 100% are bad, are perceived as good. Who cares what class the amp is if the result is good for the purpose? If you want sonic coherence look at audio amps where the brief is to just make what goes in come out louder. I've got a Behringer 2000W bass head, Class D - light and was 100% reliable and it just worked. I wanted something that was just louder than the older ones I've had. Then we went totally silent and I DI'd the bass. Sounded the same to me.
