what's the point?

I think technically all amps are supposed to sound the same below clipping, but they don't. And is probably due to coloration or so due to the designer wanting his sound signature a certain way. Just my opinion.

Simple test. Blind. With help from a barely interested gf.   I have 2 odyssey amps, khartago extreme and kismet ref.  No other changes were made in the system. The difference was, and repeatedly, immediate to 4 out of 5 listeners.  Preference not withstanding...(.Kismet for me. Others disagreed)...
that’s  enough evidence for me. And the amps were voiced by the same designer. So...test this Q yourself...take the time.  Trust you own perceptions. After all, the whole hobby is about perception. 

Once I learned to level match most modern solid state amplifiers I found the differences between them pretty subtle. For years I compared amps by adjusting the volume of the system using my ear. Well, as you can guess, I heard lots of differences that weren’t there once I started using a multi-meter to match voltage output! I still hear differences, but as I said they’re subtle.

Its all subtle. Until you develop an ear for it. Then it becomes significant.

This might not seem like such a big deal. Most people who have been over and heard a demo between any two things, even when they do easily hear a difference and have a preference still almost always they will say its pretty subtle.

The difference between my system and everything else they have ever heard, they all agree is in no way subtle. It is night and day.

And so then I point out that the difference is a whole bunch of those supposedly subtle improvements. They all add up. So don’t dismiss it. Subtle is the name of the game.

PS- When you have an ear for it then volume no longer matters. Volume is irrelevant. You hear it plain as day regardless of volume. When you have an ear for it.

I have to confess that I found the information in the link posted by to OP and the related article interesting. It tends to substantiate my own experience. If two amps have a flat frequency response between 20Hz and 20KHz and provide ample non-clipping power output to the speakers  (e.g. 300 Watt @ 4 Ohm in my case), then a listener will have a very hard time in discerning a difference between them under the same testing conditions, no matter how "golden" your ears may be.