Cwlondon: So far as I know, nothing happens to a wire over time that affects how an electrical signal passes through it. But humans do grow accustomed to sounds, and that's the most likely explanation for most of the testimonials in favor of burn-in. (Expect spirited denials, however!) When salesmen and manufacturers recommend burn-in, they're taking advantage of our tendency to acclimate to the sound. Nothing wrong with that, as long as the customer ends up happy. Just don't let a salesman tell you the burn-in time extends past the free-return period.
Burn In = Voodoo?
I have been an obsessive and enthusiastic audiophile for 20 years, I am not averse to tweaking and The Audio Critic infuriates me. However, I must admit I get a little uncomfortable reading so many posts about "burn in". While I understand that amps may need to warm up, speaker components may need to loosen up, the idea of burning in a cable or say, an SACD player just seems ludicrous to me. Unless of course, the party suggesting the burn in is a snake oil equipment peddlar and needs to make sure someone owns and uses your product for a couple of months before they decide it's really no good. At that point, of course, no one could actually remember what it sounded like in the first place and even if you wanted to return it, it would be too late. Am I being too cynical here?