What class of amplifier has the most high definition sound ?

The question does hinge somewhat on what you intend to drive. A SET can measure great into a 16 ohm resistor. It would crap it's pants driving my Focal speakers though. 

I don't consider feedback a universal evil. Like anything else, it requires proper execution. 

Class D is out of the question, DOA, given it's gratuitous complex distortion at low power levels. Class A simply destroys class D at 1 watt where a huge amount of detail resides. 

Transformers provide nonlinear frequency response, not second harmonic distortion. One sucks, the other rocks. Why wouldn't you want to just connect the output devices directly to the speaker? That just sounds smart on it's face!

There's hardly a consensus about Deviolet amps. Those things evoke some real hate.