100-200-300 hours for break in? I've been away from my head-fi rig for a while, but just got my HD 650 today - used from a seller on eBay that claimed very little use (they do appear unused). I am coming from Grado RS2i and the change in sound is really dramatic; lush is one way to put it, but I see what folks mean by the veil.
Looking forward to experiencing the "break in".
I've owned my hd650's for about 2 and a half years now, and listen to them at least a few hours a day. Mine are well over the 1000 hour mark, and they are way opposite of being muffled, and sounding like a 50 dollar pair of headphones! When brand new, they sound like an ordinary pair. Wait a month or two, and you will literally have your mind blown away! You will say, OMG! They're completely awesome headphones! And when paired with a good tube amp....well....you'll experience total audio nirvana! I know I have! here's to a happy listening.