Distance affirmation

One of the more satisfying affirmations happens when two or more unrelated people make the same sonic observation. We send out an update and emailed observations roll in. "What happened to the bottom end?" Or, "The top end just opened up." For better or for worse, it is fascinating that so many unrelated listeners hear the same sonic changes on very different systems. Were these changes measurable—like moving the -3dB point of a filter—we would be surprised if listeners didn't hear the difference. But when it comes to changes we cannot (so far) measure, it begs a question. If there are no advertised preconceptions and two or more listeners hear the same thing does it validate the change? Or put another way, how many confirmations from unrelated people does it take to authenticate an observation? I am not arguing that something is true simply because two or more people make the same observation. An entire audience observes the magician sawing in half the lady, yet we know she's still whole. If we cannot identify a mechanism for change, is what we're hearing any less valid?