Subjective proof.
A subjective proof is an oxymoron....
There is only subjective experience and experience are always subjective...
The true reason why cables importance is exagerated among audiophiles is in relation to the more impactful other urgent problems to solve: principally the 3 embeddings...
An objective proof in matter of cable is nearly impossible because of all factors implicated and also because it is impossible to reduce experiencing consciousness to numbers dials in principle....And the experiencing of cable difference is most of the time easy to test ourself by replacing one, for sure that is not a proof only an experience.... :)
My best....
« i divorce because i fail to choose my wife in a blindtest»- Groucho Marx
« After seeing God, after this experience, who wants on top of that a proof ? » -Groucho Marx