To win, you:
1. can't have an amp with crossover distortion (sorry class AB)
2. can't have an amp that isn't linear & has an output filter (sorry class D)
3. can't cheat and use a bunch of feedback to lower distortion. (sorry class AB & D).
What we are left with is Class A solid state for accuracy (pure sound?) and tubes for adding those lovely harmonics that give us that deep and wide sound stage, extra decay, and rounded notes.
1. can't have an amp with crossover distortion (sorry class AB)
2. can't have an amp that isn't linear & has an output filter (sorry class D)
3. can't cheat and use a bunch of feedback to lower distortion. (sorry class AB & D).
What we are left with is Class A solid state for accuracy (pure sound?) and tubes for adding those lovely harmonics that give us that deep and wide sound stage, extra decay, and rounded notes.