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

Roger believed in his product enough to let you hear it for yourself. To test the device in question. IOW, he put up. You, on the other hand, irrespective of the circumstances, HAVE NOT put up. It is that simple. Everything else is chest thumping.  
I have in no way said that I believe what he has said. If you could please point out where I said that, I would be grateful. On the other hand, I have not discounted it either. I am curious though, what exactly would you "risk" by listening to this piece of equipment? Your pride? Your beliefs? Financial obligation aside of course. I would love to audition one of these. Of course, IF (note I said if) I found it to do what Roger says and reported it as I heard it, I would be labeled a kool aid drinker, a dupe, and subject to confirmation bias because it cannot possibly be so. It would be better if one of the people that claims this to be snake oil actually test it in their own system and report what they heard. If you heard Roger's device do what he describes, would you be man enough to come back to these pages and report that?

Kosst

The point of this thread was to discuss Nelson’s statement that amps are a solved problem, that there is no technically perfect amp, and that they are, for all intents and purposes, art.

I understand that it is his viewpoint or opinion but it is not factual.
His mission or target or goal (according to the article) is to make an amp with a particular "sound" or signature.

Pass:

There are few things I enjoy so much as to contemplate the specific (and complex) characteristics of the many transistors (or tubes) and how they might fit into an amplifier to deliver a sound which has a particular signature.

Rather than go through all the devices as if they were shades of paint on a mixing palette - I prefer to make an amp with "no sound".  By default in order to have a "sound" the amplifier modifies the pure input signal to include a form of distortion or corruption based on the devices used. It is not necessarily bad thing but I don't want to hear the parts - the only thing I want to hear is the music.

As far as bold statements - I am trying to be polite. I have a policy of not criticizing or speaking ill of other designers. Mr. Pass by his own words is not seeking the perfect amp. I am.

I could give you a few bold statements of fact but it generally won't sit well with some individuals that post or read this thread. It would be good news for some and bad news for others.

I think the engineering science to design and produce a straight wire with gain reached sonic perfection in the 1980's. The next advance was in improved manufacturing technology that made such amplifiers considerably cheaper (unless you wanted the mystique of audiophile stuff that ironically was often far worse). Right now, and I suspect even more so in the future, the technological drive will come from the need to be more energy efficient. In Europe, mandatory standards of energy efficiency are tightened for more and more products. For example, our recent vacuum cleaner that comforms to new EU standards uses only half of what the previous premium model did, and is far quieter and lighter to carry (and it sucks dirt rather better). The same is happening everywhere, and the only reason that e.g. class A amplifiers have not yet been outlawed is that there are probably too few of them around. But new TVs have to meet pretty stringent legislation. I suspect this is a large part of what is driving class D developement.