You don’t buy an amplifier or audio gear... to measure it.... you buy to listen to it.
But you need to listen to it at home, "if" you understand the specs and bench tests, you can make a decision to take it home in the first place or not and not waste time, as dealers will sell you anything.
Also all your equipment is designed using these measurements and tests, then the designer listens to it, and if necessary makes changes using again those measurements and bench tests.
If you have any equipment that wasn’t made using these measurements and test, then you have junk!
Cheers George