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

The spec for the velocity along the horizontal (time domain) axis = constant

Amplifiers that do not control this property are not constant (unstable) and as a result have varying degrees of smear or focus issues based on microscopic time warps.

Ok here is the answer to the age old question "why do tube amps sound better even though they have higher THD?"

Tube amps sound amazing because the velocity variations are minimized. I knew this back in 1969 when I use to design tube amps.
It is why they are still hard to beat.

But - they are still unstable. Removing the variations completely gives you an amp that has no sound of its own. IOW it does not sound like tubes or solid state.

It "sounds" like air.

I am not talking specifically about power amps. It applies to all circuitry, phono stages, line stages, and analog back ends in DACs.

This is why if you listen to older recordings made in an all vacuum tube studio using tube mic preamps, they are the most stunning captures.

I have understood the "magic" of tubes for years. I would have been happy to duplicate that "magic" using transistors. Most other designers have defaulted to the second best device - the almighty JFETs , MOSFETs which because of the field effect closely approximates the more linear grid control.

That's why the popular JFET craze is so well accepted. However, they too have time warp issues that need to go away in order to compete with air which is 100% linear and has zero distortion.

OK- so this sounds like to me that the correct answer to my question is 'no'.

With all due respect I'm still not sure what you are asking.
If you want to know the value of the output velocity it equals the input velocity +/- zero.

It does not add any acceleration or de-acceleration.

The sound of a circuit is the signature of how its velocity is handled.

Are you sitting down?

I can install an auto-focus circuit to control the velocity of a tube circuit and achieve exactly the same sound as a solid state circuit with the same auto-focus. They would both produce the same holographic images.

Roger