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

I’d say about 90% of the problem audiophiles face is getting all the music that is in the grooves and all the data that is on the disc. It’s really a playback problem. The challenge is to resurrect or archaeologically dig up the information, clean it, deinterleaved it, make it coherent, so it makes sense. You are not protected by the Error Detection/Correction algorithms. Only 10% has to do with equipment and even cables.

Without tweaks, without isolation, without room treatments, there can be no high end. There is no artificial ceiling that cannot be broken through, some silly line that signifies Audio Nirvana. There is no hyperbolic curve of system performance. Hel-loo! Those who believe they only have 2% or 5% left to go before they reach Audio Nirvana are simply mistaken. You don’t know what you don’t know. 😳 Think of Audio Nirvana like climbers climbing Mount Everest. Many climbers get up one morning and declare, "Hey, we made it! What a view!" 🏔 Then they’re informed, "Dude, chill! We’re only at Base Camp." Which by the way is only half way up Everest. 😛

ok, now I’m curious - where can I read about the advances in understanding human hearing & perception thereof (psych. not physiol.) since the 1960s?

You gotta pound the heck out of google. Here's a fun one:

https://pdfs.semanticscholar.org/2f03/7a2adec2af5953b4f84ca6b2e2b3f30a3bf3.pdf

And its the tip of the iceberg. Note how the limbic system is involved...  more:

https://pdfs.semanticscholar.org/2f03/7a2adec2af5953b4f84ca6b2e2b3f30a3bf3.pdf

GE did a study back in the 1960s that showed that the brain uses higher ordered harmonics to gauge sound pressure, but the study does not appear to be online. However this particular fact is easy to prove with very basic test equipment. Oddly though, the implications of just this fact are largely ignored by the audio industry.

Going even further back, we've known since the 1930s that certain harmonics have certain audible effects, for example the 7th can impart a metallic quality (and in small amounts; see the Radiotron Designer's Handbook) but this fact again is largely ignored.

Which is why I chase after the removal of all metals that have hysteresis issues, when involved in an audio signal. This delayed response tends to contribute to the harmonic structure of the end signal, smearing it across time and then being heard as 'loud' when it is merely obscuring metallic sounding distortions which are stretched in time.

audiophiles are so inured to this sonic aspect that they many times don't recognize a truly correctly delivered set of intermixed transients.

Or they do recognize the noise and employ gear or cables that swamp it with damping distortions, and dull the irritating aspects out. Then the next piece in the line of gear distorts and exacerbates the transient noise problem again and then the next cable or speaker or whatnot, blunts them.

They end up with a system that is built out of 'dulled screech' and then wonder why they keep changing gear out, over and over and over and getting to exactly zero fidelity.

There is no magic single bullet in any given system, there is only all pieces individually doing their best to not damage the signal--but more importantly, not add to it.

Yet we are wired to seek out this micro detail, due to our biological function.

It' a complex affair that requires some notable mental wrangling and retraining of hearing function.

Most people won't work on themselves, they project, as that is what ego does. With music we do so very much engage the wiring of survival and bodily procreation (music hits the same area of the brain as sex), thus we engage the blind side of the ego and it's projection.

Thus the audio arguments and intractable positions and the unending battle to have one's projection be the real one for all (ego demands that the world reflect). This is stuff is taken personally, all affront, all the time. Our balls are on the line. Literally. At least as far and mind and body are concerned.

Underneath this gigantic projected mess of an audio world, there is some basic truth but it tends to be the path less traveled. The best gear is known by less and less people while mediocrity has the lion's share of the sales. This is true in any commercial endeavor that has a large cross section of humanity's possible characters involved in it.

With all this and much more in mind....with the liquid metal wire, I went right after the fundamental carrier itself. I went after the complex impedance expression, right where it is created or interacts at the atomic level.

If you take strands of the liquid metal cable and make coils out of them and then play with pulse aspects, you will get some interesting differences that cannot take place with 'wire' coils. Fundamentally different.

Wire (solidus lattice organized elements and alloys) may be the best common carrier for electrical audio signals (complex ac expression) but it has it's issues. Complex LCR is tied to these aspects of atomic structure. Which we tend to try and ignore or not recognize as it has been here since the beginning of 'electricity'. We simply don't know any better.

Fundamentally different electrical expression is not snake oil, its just very very new and not really understood as of yet, with respect to written works that come from sussing things out.

The original question had to do with psychological not physiological issues related to human sensory perception. For the answers to that question one has to think outside the box. Outside all the boxes. This is Peter Belt territory, and Rupert Sheldrake and David Bohm territory. One of the best, though would certainly appear to an extremely unlikely place to start, is Rupert Sheldrake’s landmark book, The Presence the Past, which has to do primarily with memory and behavior of animals and defines Morphic fields. To cut to the chase, this all has to do with how our local surroundings influence how we hear sound. It is what I refer to as mind matter interaction. It can be a conscious or a subconscious reaction to shapes, materials and words and phrases and symbols, such as barcodes and logos. The good sound you worked so hard to obtain is actually there in the room. You just aren't hearing it correctly, that's all. You think you are. Why wouldn't you, right? But you're not. That's all for now. See you later...