well they have gotten MUCH better sounding over the years.
Sorry I don’t agree, the ones with static set Class-A bias "if in good operating condition, to me sounded better than the ones with auto Plateau (sliding) biasing.
The very best highest Class-A without external heat sinks if in good nick were the early KSA50
https://www.stereophile.com/images/99krellksa5041279.jpg
or the better more powerful KMA100 monoblocks which were both chimney fan forced heatsinking and biased statically very high into Class-A.
https://www.flickr.com/photos/mracoustat/5419823759
Cheers George