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

No - the future is already clear. The new switched Mode Power Supplies are reducing 60Hz hum and lowering noise floors further than ever before imagined with a linear power supply.

Look at the specs on a Benchmark ABH2! Can anyone find an amp with better performance specs?

Only a few years ago world class was around -110 dB SNR, THD etc... these improvements are nothing less than staggering and YES you can hear the extra definition, clarity or blackness that such performance brings even though the best speakers are only -70 dB in performance. (I was doubtful about whether this level of performance can actually be heard but my ears tell me otherwise)

maybe the Future is already here and we are at the very end of technology breakthrough regards to audio?

Class D is a poster child example of modern day innovation in audio amplifiers. It is indeed SOTA in some spectacular designs and will only get better. I suppose many manufacturers, Pass Labs included, are a tad offput at the fact that great sounding amps, amps that cost and weigh a small fraction of theirs, are becoming readily available. The fact is we are in the midst of disruptive amp technology. It is pretty much the opposite of the article’s suggestion in amplifiers.

Class D is still in process, but great sound is already out there. How can we dismiss this reality? Strange to me how when in the very midst of innovation and change some still miss it. Some that should, and probably do, know better.

Tommorows’s Class D amps will be wonderful, but some will still prefer a tube amp or this other amp etc... This will always be the case as choice is so very important as we all hear differently. However, dismissing  the Class D evolution/revolution is startiling.

Combining Class D with high quality DACs (powered dac) is another fascinating innovation hot bed.

The Map is Not The Territory.

A wanky and side shifted statement might be that Class D is about solving a problem that no one in the world of high end audio was interested in asking.

Further... in the world of stately posturing (why back down when you can double down!): For me, an innovation has to exceed what I know, almost from the get go, not spend 20 years in the middle of a fistfight argument about barely equaling it. Like Digital vs analog.

Human spheres of communication and awareness/sharing, social grease, clannishness and so on. Marketing..being a thing that works..speaks to the eternal shame of some of humanity's complex integration(s).

Our amps are really not spinoffs of anything. And they are tube. So I don't agree we're at the end of the line by any means...

But to make it more interesting, we've been working on a class D amp of our own for which we're also working on a patent. Not going to reveal too much, but we solved one of the major sources of distortion in class D amps. And we have proof of concept.

Now if we can do that on no budget and without any prior *recognized* expertise in the field of endeavor (people tend to think that just because we only do tubes that we can't know solid state as well, as if solid state is not taught at the University of Tubes or something...), what does that tell you? That perhaps there is still more to be done?

One area that is a problem for all amplifier designs is that most are designed to have specs that look good on paper and are not really designed to also sound good. Now this is a simple engineering problem (understanding the rules of human hearing and designing to those standards rather than the existing set of arbitrary rules); the bigger problem is tradition- the tradition of how we say what are good measurements and what are not is at the heart of the issue. How do you get the industry to move off of standards set in place 60 years ago??

Until we fix *that* problem, progress will only be had by the outliers who are willing to buck the tradition and pay the price. And they are out there.

Some years back I had some troubles when some people tried to steal my company. I remember getting a call from David Berning, who simply called to offer moral support; he told me (paraphrasing) that 'the industry needs people like you that bring diversity to the field'. I really appreciated hearing that from him and who better to say it as he is exactly one of those individuals: a brilliant designer and no-one makes amps like he does either!

There are brilliant designers in this field and there are those that recognize that if their amp is simply competent, someone will buy it even if it is a rehashed 1950s circuit. I don't see that progress has slowed down at all- if that is what Nelson (whom I see as one of the world's top designers) is saying then I disagree! I do think that we see a lot of derivative circuits but we're always going to see copycats.