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

Feel free to augment or quibble, but I would call an "objectively audible difference" between amplifiers as follows:  when the equipment is gain-matched to be sure the difference is not simply due to different overall volume levels, listeners can still repeatably distinguish between different pieces of equipment *only by listening*.

After reviewing what I can find online, it seems people, audiophiles and engineers very much included, have a lot of trouble with that, especially with respect to cable, differing digital resolutions,and reasonably powered amps that meet or exceed (essentially mid-fi Japanese) distortion specs. 

I see a lot of people here asserting confidently that they can easily do this, but not a lot of verifiable evidence.  That really  piques my curiousity. Although we are talking about amps here, I'm even more curious about high-res digital.  

Even if I came away fully convinced of an extreme objectivist case, I would still probably go for lower distortion, high quality amps, I would probably still by high-res digital (after all, it should  speak to the company's dedication to high audio standards) and I would still audition equipment mostly to ascertain whether the experience was likely to give me pleasure every night, as opposed to just on paper.   But I'm very curious, and I think hobbyists (but perhaps not dealers who rely on the constant tweak & upgrade cycle) would benefit from an open mind..

btw, I totally reject the idea that only self-appointed "Golden Ears" should engage in this discussion.  That seems not only snobby and unintentionally hilarious, but far too exclusive for what is, sadly,  a hobby seriously on the wane.  Don't you agree? To say otherwise seems like a formula for devolving into incestuous irrelevance.

The reality is, if we all, the audiophile community, heard no differences, wouldn’t the high priced gear go bye bye, or, just 1 or 2 manufacturers would be left for all of us ?

I'm not sure. First of all, we'd have to concede we don't hear differences, second, we'd have to decide that the other expensive hallmarks of quality don't matter enough to pay for. Finally, there are still features, appearance, and ergonomics to consider.  In sum, no, I don't think it would change as you suggest.  Consider the high-end watch business.

You bring up the sommelier analogy. I've always considered it a point in that industry's favor that it's highest accreditation requires an incredibly difficult blind (to label) identification process.  But even in that test, there are many other hallmarks other than taste (color, viscosity) that inform the well-defined method that passes the world's hardest test.  There is a great book about that called "Cork Dork" by Bianca Bosker, I highly recommend it -  if you can accept a referral from a "troll" such as myself.  Yes, I like wine as well, and I'm certain that enormous amounts of contextual subjectivity enter into my evaluation of each sip, and I'd love to understand it better.  That, rather than stuffy assertions of exclusivity, is what the hobby is about.

@atmasphere   You bring up a great point! What is "objectively audible"??
I suspect that "objectively audible" is going to be far more objective to some than others. Possibly those that have made up their minds in advance that no such audible differences exist, will get their expectations met..and will NEVER hear any differences.

Ahofer, you never responded to my comment, as to why you own expensive audio gear ( what are your components ? ), as I suggested, simply for prestige. And comparing it to a watch ? Maybe, if it is all about prestige. I believe my comparisons were more legitimate, as it showed a certain ability, familiarity and expertise, by the individuals, in their respected interests and fields. You are welcome to go on and on, but simply, I will no longer respond to you, as this " need to know " thing, is " your " thing, not mine, or anyone else’s here. So take care, and Enjoy ! MrD.

Ahofer, you never responded to my comment, as to why you own expensive audio gear ( what are your components ? ), as I suggested, simply for prestige. And comparing it to a watch ? Maybe, if it is all about prestige. I believe my comparisons were more legitimate, as it showed a certain ability, familiarity and expertise, by the individuals, in their respected interests and fields. You are welcome to go on and on, but simply, I will no longer respond to you, as this " need to know " thing, is " your " thing, not mine, or anyone else’s here. So take care, and Enjoy ! MrD.

I did indeed respond in full (I have no problem enjoying it regardless of what I learn or unlearn), and I've described my system elsewhere on the forum. I can't make coherent sense out of the rest of your comment or claims of "legitimacy" whatever you mean by that.

But, by all means, show me the evidence I have missed or ignore me if you don't want to spend the time. That would be the best course of action for everyone.