What class of amplifier has the most high definition sound ?

+1 @douglas_schroeder -- but the fact remains, when all other pieces of the audio system are dialed in and set, the amp choice still matters. As with everything in audio, the chain is only as strong as its weakest link. And you can carry that down to the design of the amp itself. No matter what class of amp, all the other design parameters and choices affect the final outcome. So while I might prefer the strengths of a Class A amp in general, I’ll take a well-designed Class AB amp over a poorly-executed Class A amp hands down.

I have heard many SOA contenders & with a compatible pair of speakers nothing has ever matched the purity of an OTL.  I remember the first time I heard a Futterman.  It was certainly dirty sounding (enough to disqualify it in many ways),  Even so it had a purity in the upper midrange in particular, that was unequaled by any objective or subjective standard. End of story. By any amplifies.   A high quality OTL wiil far surpass it.  I don not own an OTL.  The speakers required are not anything I've encountered so far.  Nevertheless it is & no class of amplifier I've heard comes up to that standard. None.  Although there are some pretty wonderful ones for other kinds of systems that overall may be better compromises.

soix, I concur; we are not in disagreement. We may vary on what we feel the degree of contribution the amp (whatever type) and the system contribute, but both are critical to desired outcome, and everyone will have their favorite genre of amp. Absolutely, the quality of the amp in the chain is critical! And, people will feel strongly about the genre of amp they think is superior. 

A. Nothing is better, except maybe single ended class A.

Give Spectral a try. There are a number of reasons you may find it rewarding. Resolution combined with macro and micro dynamics. Utterly uncoloured. They are fanatics; and Professor Johnson has never been influenced by money or short term gain. It’s a very unusual company; a pure pillar of truly high end audio.