I thought valves that aren't required to deliver large currents, have well designed circuitry and sport quality custom wound output transformers, should sound very close even undistinguishable from good SS. To reuse an old real estate saying, implementation, implementation, implementation. Speakers who require high voltage but low current like ESLs, as well as high efficient dynamic speakers (large volume cabinets, large diaphragms, high density EMF alnico or neodymium mags) will do well with valve amps, the technology of its time.
As for Class A, I think it usually is a snob or an OCD thing (or both). IME the audible benefits are miniscule compared to the downfalls. Low power, high electric bill, larger space needed in your living room (I wouldn't buy Class A gear again unless I have dedicated listening room) and high cost of buying the actual gear. Is Class A technically superior than AB, B, D etc.? Yes. A yes but at a cost, which in the end may not translate in a higher fidelity sound. Why?
I'm talking true Class A here, not quasi A in the form of high biased AB like MF A1 or Marantz PM-80. I mean 2A of current burning through those transistors, large heatsinks outside the case etc. To reduce the cons of owning a true Class A topology amp, people buy small integrated amps (small compared to a Krell KSA-100) at the cost of lower power output available to the speakers. This means they limit their choice in speakers, the largest factor of sonic performance in the hi-fi chain.
Cno could have bought better speakers than the KEF R700s if he settled for a more powerfull and cheaper Class AB amp (compared to his MF AMS35I - 35Wpc), thus yielding much higher fidelity than he has at this moment. Boggit transitioned forward by selling the 21Wpc Sugden, getting high quality speaker kit from IPL, a not so well known manufacturer compared to KEF, and opting out for a high current low TIM amp, the Abrahamsen V2.0 UP. This would be a step forward in fidelity compared to Cno IMO, presuming the IPL drivers are better than those by KEF. And I mean higher fidelity in the sense of live performance, larger than life sonic immersion. I consider Electro and Lindsayt as wisemen gear druids among us and I think Boggit did the right choice taking advices from Electro regarding amplification.
However, if Cno is a Class A (OCD) afficionado and in love with his amp, he deserves no criticism. He enjoys his own thing and that is all well and good. He waves his pom-poms for Class A, like I do annoyingly for AB. We keep the forum annoyed/entertained.