Let us suppose that a golden ear audiophile or cable developer can get a 25/25 score ABX test on cables. Will it universally prove that cables can make a difference?
Of course not. It will, however, if the result can be replicated either by that person at a different time, or by multiple people at once (remember, it's entirely possible for one person to flip a coin and come on a run of 25 tails.) prove that one cable
can sound different from another.
If there are no measurements that adequately explain why that cable sounded different - for example, I could once tell a difference between an MIT speaker cable and something else on a pair of Martin Logan Quest-Xs, but that was just because the network on the MIT was a highpass filter that measurably rolled off the highs at least on a panel speaker with impedance falling with frequency increasing - that would be a
bombshell result.
Until/unless a measured phenomenon was found that was then independently correlated to the observed sonic difference, such a finding would literally destroy the whole objective "audio is engineering, not magic" mantra of rational music lovers. (I hate the term "objectivist" because of its political overtones.)
Yet no wire company has been able to (legitimately) create that result. Does anybody
really wonder why?
Or should we have an individual ABX examination before being able to buy expensive equipment?
You are making the unwarranted assumption that people buy "expensive equipment" exclusively for sonic reasons. In truth, there are many other legitimate subjective reasons to pick one box over another that have
absolutely nothing do to with sonics. I bet there are a few people, at least, who are buying Lexicon's BDP-83 recase even though they KNOW it's a BDP-83 with a ~$3000 premium for zero sonic gain. However, they might want to match their other Lexicon gear, they have a good rapport with a dealer who will come and set it up for them, they might like the display color better (the Lex puts a filter over the BDP-83's display) or maybe they just want to be able to say "my player cost more than yours." Whatever the reason, so long as it's not based on sonics (we are, after all, talking about
identical products, except for the recase) it's entirely reasonable.