Well, orthodox 'science' as it stands today would have us believe that many differences claimed to be audible are not. At least the vast majority of voters here would accept the possibily that the differences could be imagined, which is what 'science' infers.

Whilst it may be misplaced enthusiasm, it is not unknown for claims to be made for cables etc. along the lines of 'a total transformation of the sound', couldn't believe what I was hearing', 'one of the biggest improvements I've heard'.

A poor analogy but would it be possible to imagine such gross differences between, say, two identical paintings? Visually, I don't think we would be able to fool ourselves to that extent. Of course, it is also possible that cable believers are not fooling themselves - or, in other words, science is wrong - but how can we find out?