Are future improvements in Amp/PreAmps slowing to a crawl?

Pissing contest. That's exactly what Pass was talking about - a lot of that but virtually no progress.
I won.

I mean it cannot be fully recorded, I did not say that it cannot be recorded well except big orchestra opera and big choral pieces - this is especially tough.
In any case, I believe that amps and wires without gain are already quite good, that is not a major problem. Turntable set-ups and open reel decks are quite good too. Problems are the recordings themselves and speakers. The beginning and the end, the middle is acceptable even if it may cost a fortune to be that.

Microphones cannot 'hear' everything so those designers were right anyway - music can't even be recorded as performed let alone reproduced. And I think this is good. Let the chase continue forever.

Great. 

Then, Ralph, I have a suggestion. Why don't you design a hybrid integrated amp at the level of Ypsilon or beyond with a great phono stage? And not $25k one.

Why would a respected tube amp designer want to play with something very different?

I think, he is both right and wrong. He is right that there doesn't appear that much more can be done with either tubes or transistors. Breakthrough will come when something different is invented. Whether it is ever invented or not is another question. I hope so. Let's be clear about it - neither tube nor transistor is good enough.
He knows it but he sounds quite resigned.