What class of amplifier has the most high definition sound ?

I would say it somewhat differently - tubes presenting harmonically correct soundscapes.

Only Class-A OTL's, anything with an output transformer is hamstrung.

Cheers George 

analogluvr
I would say OTL class A

Ditto that.
But there aren’t any speakers "THAT I LIKE" yet without any colorations that they can drive with ease (without bandaid fix autoformers), top to bottom, so "TO ME" your ****** if you do and ****** if you don’t.

The only way is to make a hidiousely big OTL Class-A with a bazillion tubes, so they could drive hard to drive speakers speakers that are designed to be flat, low coloration, low distortion and without horns to make them efficient.

Cheers George

sacresta OP
Ok guys, my question was focused in experience and sensitivity to pure sound.

"Pure Sound"?? Class-A OTL tube wins, with heavy proviso's on what they can drive. After which come Class-A solid state, which can drive most things if good designs. 
SET and all other tubes are governed by their output transformers, they are not "pure in sound" and have colourations.

Cheers George

Class D amps take some meat off of the bone. It can come off as crystal clear, defined, and completely quiet between notes (inky black) but to my ears that sound signature is the result of removing a tiny amount of the music from the source. My guess is that its a product of the output filter, a tiny amount of the good leaving with the bad.

"a tiny amount of the good leaving with the bad."

The bad being "switching frequency noise".

Trouble is, there’s still a lot of the bad left behind, with today’s Class-D topology.

Best, least coloured, fastest, cleanest, most dynamic a Class-A OTL tube amp, trouble is the speakers they love to drive are the "polar opposite" if full range 20hz-20khz.

Cheers George