I know nothing about Class D, but will look into it. Mainly, I wanted to support your conversation regarding boxes. When I opened my shop in 1974, I thought I knew a lot. HA! After locking the doors every evening, the real work began.
I learned VERY QUICKLY that ALL boxes distorted reproduced music. My guitar and bass amps are boxes, but they are built for a different purpose than hi-fi speakers.
The real revelation, after learning about box speakers, was listening to the ever-popular Bose 901 hot mess and then turning on a set of Magneplaners driven by Audio Research gear of the day and a Linn Sondek with a moving coil cartridge. A Lincoln Mayorga Direct-to-Disc source finally got me to put down the guitar and listen to recorded music.
There it was, and I have never looked back.
Certainly there are many boxes today that are much more refined and have much better engineering than they did in the 1970's and '80's when I had the shop, but they remain boxes.
While I understand different strokes, I still find it interesting that people will not even try Maggies before dropping tons of money on boxes. My point is, at least try them in your room. If they don't work for you, at least you will know that. And, you might learn something. Imagine that!
Cheers!