Why is science just a starting point and not an end point?

Test tones also shows how equipment performs at listening levels

No they don’t. Some of us do have hearing that is both sensitive and reliable enough that we don’t need to a scope to tell us if we heard something or not. 

Look at Prof's post above then read the book mentioned. Nobody's hearing is reliable enough. 

but how music performs at listening levels is the deciding criteria. In that regard science fails miserably.

That’s your opinion

Some of us do have hearing that is both sensitive and reliable enough that we don’t need to a scope to tell us if we heard something or not.

That’s is really wishful thinking and believing your hearing is better than a bat.

All "good equipment" is designed and made using the "Laws of EE" (Electronic Engineering), and the measuring and test gear that designers use to do it with.

"If" they don’t like what they hear or measure after it’s designed and built, good ones will go back again and again and redesign things in the circuit, and re-test, but do it again using all the same EE laws and test equipment, there’s no voodoo involved.

IF THEY DON"T DO IT, DON’T GO NEAR WHAT THEY ARE SELLING, BECAUSE THEY ARE SELLING YOU VOODOO!!!

Cheers George

Ooooffff.

Good science is a very high bar.  A theory must be proven universally true.  That is why science is always a long way behind conjecture.

But that is no reason to ignore good science and live by conjecture, as apparently do many people here.