How far have ss amps really come in the last twenty years?

as for the insight on amps have reached their zenith, and or are all alike now, well, that is pure nonsense.

neither are they indistinguishably similar in build, they are different sonically as well.

just my input, mind you, but I trust my ears and hear distinct diffs from many amps and preamps when both are of the same brand or house sound, or as separates which has been my usual path for building a system.

naturally the only true way to ensure or prove positive once and for all, would be to have several amp makers gear set onto the same brand rack with the same source device and roll them into a room with a pair of speakers which have been optimized for that room and play them all one after the other off a set playlist.

this scenario ain’t ever gonna happen.

another way to get the evidence all amps are not equal is to buy some and listen for yourself.

this I have done along with so many, many others and found out as said, amps are NOT all alike or even too close to call sonically, not even SS amps regardless their classifications.

its ridiculous to believe they are!

of course for those who actually do believe amps are more alike than not, it is sure gonna be a cheaper and shorter path to their audio Nirvana.

they could simply buy a Bose setup and be done.

on this topic….
to get deeper insight or just some texture, on amplifier innovation, design, and concepts this link reveals an article which addresses major amp icons thru the years and those people responsible for them.

https://www.theabsolutesound.com/articles/the-12-most-significant-power-amplifiers-of-all-time/

I found the most interesting part the time frames for these designs many which date well back into the 20th century, and how ground breaking many of these products have stood the test of popularity and time together, remaining viable and often sought after products even in today’s market.

until we see plasma conduits carrying anti matter fueled power supplies, or photonic signal converters or the like amps aren’t going to see much of a complete face lift in the near future.

what role will amps play when the sOTA finally arrives at life size Hallograms in the home?

someone is gonna have to figure out how to get point source audio info from every axis within that setting to coincide with the visibly displayed content… and I think we’re back to converting electrical signals into and back from photonic means.

the curren optical fiber conduit merely carries a signal, it does not develop or manipulate it what so ever, it is just another kind of wire or pipe information passes thru and nothing more.

to accomplish it, will take a new kind of ‘wheel’..

I am sorry, but neither Pass nor Curl can compete at the top level. Perhaps they are doing something wrong.

:)  Nelson's SIT amplifiers are some of the best sounding out there. But they are only available in kit form IIRC. SITs went out of production a long time ago.

Regarding John Curl, isn't he the one behind the Blowtorch preamp? That is one of the very few solid state preamps that has developed a legendary status.

Distortion is an interesting term. Distortion compared to what? You mention that the human ear treats 2nd and 3rd harmonic distortion favorably. Therefore, one needs to question whether these distortions are distortions at all. Since we, as humans are using our ear/brain to determine what is considered as a true  and pure signal, wouldn’t it make more sense to label a signal that doesn’t include these 2nd and 3rd harmonics as the signal that is actually distorted...?

Even though they are beneficial in many ways they are still distortions. This is why there is that term 'euphonic'. I've often felt though that distortion harmonics should be weighted according to how important and audible they are to the ear.

It was a sign of the times that Curl et all went to Parasound about 20 years ago and abondonded Blowtorch preamp and the Bar B Q amp which were very high end components. I participated with Curl and Crump (TG Audio) the last year they exhibited the BAR B Q with the Blowtorch. The following year 2001 the JC-1 (scaled down Bar B Q) debuted with Blowtorch and Entec Number Cruncher DAC. I isolated the Blowtorch, Entec and four (count em!) JC-1s that year with a one of a kind double decker Nimbus and four Promethean isolation bases.

I suspect that just like loudspeakers, when the amplifier designer engineers an amplifier to fit to a certain price point, he is also targeting an amplifier sound that he thinks best presents music as realistically as possible.  In other words, its not all about perfect square waves, SNR and THD.  Therefore, its reasonable to expect that different designers have different ideas of what sounds right...hence amplifier will sound different.

As Blindjim said....just try a few amps and it doesn't take long to see that either the amps themselves sound different....or the way they interact with the rest of the equipment results in a different sound.

Right now, I'm "trying out" a new amplifier called the 2Cherry from Digital Amplifier Company. Its class d, no modules, all in house designed circuitry using discrete components...and boy does it sound good...open, three dimensional, detailed, liquid...I could go on....for less than $3k....so I think there may well be room for continued amplifier development.

And in a way, I agree with Atmasphere...most of us say that we want as little distortion as possible...but I think we really want is what sounds the most like trumpets, pianos, guitars and voices that we have heard live...and maybe sometimes, to some listeners, a euphonic presentation is more pleasing.