What class of amplifier has the most high definition sound ?

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. 

Hi there
We can get the most natural sound from class A amplifiers. They have "soft" distortion spectrum and they are stable for pulse signals because of stable power consumption. But they produce some specific problems too. Open my page in LinkedIn (Vladimir Benkhan). There are couple articles about it and a description for simple class A amplifier.

The amps that shine in class A are the pre-amps .

You can listen to an amp that that tested off the charts in the lab, has the greatest reviews, in your setting sounds sub par. I think end of the day, it’s the pairing, room, setting, and the hearing and how one process the sound and the music. I’ve had $$$ amps and tried low wattage boutique amps that sounded better, to MY ears. I’ve had arguments with friends that tell me I’m foolish for spending what I did on gear, and say their blu tooth speaker sounds great.  End of the day, there are more factors to the equation.