The Audio Critic

The Audio Press review disputes the "every properly built amp" sounds the same or  that solid state can be made to sound the same as tubes. Nobody but nobody, however, will ever take the challenge and do the ABX testing to disprove his claims.  

If they measure the same they will sound the same-take the test to prove otherwise.

@busboy

Nobody but nobody, however, will ever take the challenge and do the ABX testing to disprove his claims.

Alan Shaw of Harbeth once offered a pair of free top of the range Harbeth loudspeakers to anyone who could demonstrate that they could hear a difference between 2 different amplifiers.

There were no takers.

Then there was that infamous episode known as the Carver Challenge.

Bob Carver once claimed he could make a $700 transistor amp sonically indistinguishable from any high end amp.

Gordon J Holt and Larry Archibald disagreed and scoffed at this claim. After some careful thought they chose an unidentified high end tube amp that was only much later revealed to be a Conrad-Johnson Premier Four.

Much to the dismay of the Sterophile reviewers, Carver did exactly what he had claimed.

Thankfully the article is still available and it remains one for the ages.

Is it possible to make a $700 "mainstream-audio" power amplifier sound exactly like a high-priced perfectionist amplifier? Bob Carver, of Carver Corporation, seemed to think he could, so we challenged him to prove it.

The question posed above seems laughable.

....

But everyone has his limits of capability, and pride goeth before a fall; when Bob claimed, some time ago, in conversation with Stereophile Publisher Larry Archibald, that he could make his $700 Model 1.0 amplifier sound "indistinguishable from" any amplifier of our choice, we were confident that he was finally out of his depth.

https://www.stereophile.com/content/carver-challenge

A few years ago, Michael Fremer agreed to a cable challenge as long as the test would be done in his listening room, which sounds like a reasonable condition to me.  The cable manufacturer backed down that time.