There is proof in the Sound Science part of this forum and for further reading google audiophile cables and then you have to sift through a mountain of bunk, flame wars and trolling. I agree the debate has never been settled, but I do think that the evidence for and against cables affecting signals, how audible the effects are and whethercable companies can justify their claims is pretty settled.
I know I know, just being silly. I've read some (too much) already and participated in some (unfortunately). I see how both sides are right in what they say but yeah unfortunately it gets way too heated.