I was at an audiophile show recently, and spent most of an hour talking to an exhibitor who just happened to be the founder and lead designer of a high end amp manufacturer. He probably wouldn't mind being identified, but since we were just talking off the record, I think it would be unfair of me to name names. Wanted to write down some of the discussion while its fresh in my mind.
Basically, he has been designing high end amps for 30 years, designed and manufactured in USA. Their kit generally runs from $10K to $100K and above per unit.
Let me just render this in first person, pretend I'm him, and paraphrase the answers to my questions.
"There's no accounting for taste, but tube amps are total ********. They do sound different, but it simply because the circuits introduce resonance into the output. You can see it on the scope. On top of that, the voltages required are dangerously high. I'm all about THD, and you sure won't see me sticking a transformer into the output phase of any of my circuits!
Back in the transistor world, in all frankness there's nothing new under the sun. The basic amplification circuits haven't changed in decades and probably won't. Sure, the components themselves sometimes get more reliable.
But there's one other myth I'd like to lay to rest. The idea that simple circuits are always better. This is another zombie myth that just won't die. That feedback is bad. Yes, there are amps with simple circuits, but they have high distortion. This myth got started decades ago when the early op-amps had high distortion. Nowadays, we can build perfectly excellent amps with more complex circuits that use more feedback. It all comes out in the wash in the THD numbers. At the same time, I do plenty of real world testing with sound engineers, or what some people call golden ears."
I wish at this point I'd asked him about that class-T craze from back in the day. He was however, by his own admission, an analog designer. Thus I was not surprised that he was a bit skeptical of Audyssey. He was not opposed to it, but the question to ask is what those (digital) filters introduce in terms of distortion. Really he was just a bit old-school about it and recommended that we all get back to some good old fashioned room treatment to soak up echoes in both the bass and the midrange. He likes a dead room.
Whether your ears are golden, silver, or bronze, he felt that many of his dealers would be willing to lug one of his amps over to your house and do some A/B testing with your existing amp. He said yes, its true that the first investment should be in speakers. But that once decent speakers were in place, you could absolutely hear what his amps do for you and why their price is justified.