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

@parrotbee 
" I guess in terms of sound quality - gains will be marginal..."

There is a way to obtain massive improvements in sound quality. At some point there will be a realization that the missing link in analog amplifiers is how much attention is given to the velocity of the [music] signal passing through the amplifier. Unstable velocity creates an image that appears to have sonic "vibration". In much the same way as there have been great strides in discovering ways to limit mechanical vibrations, the same negative vibration effects can come from the electronic circuitry itself.

When this is addressed a radical drop in "interference " is removed from the image. As the electrical vibrations become less and less it begins to move in the direction of more and more "live". This is because "live" has no vibration interference. It is the loss of vibration interference that is recognized by the brain as a live event.
 

"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance."

Orville Wright

"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance."

I believe in Quantum mechanics.

https://en.wikipedia.org/wiki/Quantum_mechanics

"I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success... such emotions make a man forget food, sleep, friends, love, everything".

(Nikola Tesla)

After decades of research...
Welcome to my world.

Roger

I see two things improving these days, DACs and class D power amps.

Other than incorporating new, more capable DAC chipsets into new preamp models, I agree with others who have posted here, that the preamp itself isn't really improving.  In my case, I have never used the DAC in my preamp, I went with an external unit, one based on an FPGA chip, where firmware updates improve the performance of the DAC, like getting a "new" unit every year or so!

I must admit that it's been years since I auditioned a class D power amp, and back in the day, was not impressed with the sound (to me it sounded "brittle").  With all the new class D designs, eventually I'll take the time to update my experience with class D and audition some of the new amps.