Cables don't need to be burned in, I'll agree with that one... Their conductivity levels will remain, actually, a new cable (brand new) is better than a really old one since everything eventually begins to decay (but it's not an audible difference). They have no moving parts (unlike drivers, Armatures and Dynamics alike).
That is the main argument for driver burn in, they have moving parts, and right off a production line, nothing is ready to go 100%, they have to be "broken in" (like a new pair of shoes) so the diaphragm, and other moving parts have time to be more "active". Because I've actually heard this happen first hand after getting my ADDIEMs replaced (new sound -> used sound; back to new sound -> old sound) with no changing of anything (like tips, seals, etc; making it a controlled experiment), I believe in burn-in. You don't have to, I'm not going to make you believe in it, it's insane to do that.
The main arguments against it are placebo effects, change in seal, and getting used to the sound. The reason why this argument won't get anywhere is because both sides need to be able to be tested, the placebo effect can't be tested at all.
Even with all that, what's the point of arguing... If you burn in a pair of headphones before you review, it won't change the sound if you don't believe (so it won't skew review results) and it will have it's final signature if you do believe (so it won't skew the results either).
Does burning in work? Does it matter?
@OP, burn them in (it doesn't hurt to do it) and see for yourself, does the sound change? See for yourself, as no one can force you to believe in burn in, no one can make you not believe in it either. It's one of those things you have to find out on your own.
Edited by tinyman392 - 6/21/11 at 3:35pm