When I was like 23 a bored guy in a HiFi shop, who obviously knew I couldn’t afford anything at all in the store, did a blind test with me using stock power cords, $300 cords (which blew me away at the time that they actually existed) and a cord that costed thousands. System was Krell monoblocks feeding B&W 800 speakers. I had never heard a system worth more than $8,000 up to that point. Anyways, I correctly picked the right cable every time. Being able to blind test and pick the cord with 100% accuracy was all the proof / measurement that was needed.
I can still perform this test with 100% accuracy at home. Really, no other measurement matters if you can objectively hear the difference and identify the cord without knowing which cable is connected.