never heard someone say you can compare two amps with different speakers, that sounds rather extreme haha!
Heard this countless time, AFAIC.
Typically :
I've listened to x amp at a store, it sounds dramatically less musical that y amp (that I tested at home).
Not the same room, many times not even the same speakers, and most importantly, not even the same day... But they call it a valid A/B comparison all the same.
The same way, when you sell an amp on the second hand market, people always want to come to your home for a "listen" (I'm not talking about testing if the unit just works). Nonsense, but a true thing for many audiophiles.
It’s even more common indirectly, some people are attributing a common “house sound” to some electronics that somehow pervades trough every kind of setup and situation imaginable
The perverse things is that some myths can be self fulfilling, this kind of thinking has gone full circle several times and there are actual products designed by “gurus” that thrown away thier engineering education and does things differently because ( insert any dumb thing here / feedback is bad / filter ringing / toobs ). It can be soo bad they actually manage this .
A thing to think about when discussing electronics. Many here including me are just assuming normal,sensible engineering practices . And then products should work in a predictable manner fr is flat noise is low distortion is low, directivity is predictable and ok crossovers makes sense etc .
And we have amirms literal pile of transparent DAC’s that all sounds the same to a human listeners ,he must have sitting somewhere
Not always true with high end stuff, it sometimes a parade of bad choices and yes sometimes manage to “sound different “.