Really? Here's some great information on the "burn-in" for dynamic drivers. Maybe, orthodynamics are different with respect to this process. However, the numbers are factual.
I've read a decent amount about speaker burn in, but nothing on headphone drivers. Since the dynamic speaker, whether it be in a headphone or just a speaker, performs in the same way, I would assume that the dynamic headphones drivers will "burn in" a little bit, but enough to change the sound dramatically like with speakers? I doubt it. The reason is because speakers move a lot more than headphone drivers do in order to push enough air to make sound for an entire room. This requires much more driver movement than a headphone driver does (I don't think that the displacement/dB ratio is linear either). Breaking in a speaker just makes more sense to me I guess. Planar magnetic drivers are a whole different ballgame too.
Thanks for the link, I haven't seen this article before.