Here's an interesting story.
My HD800s ( SN: 11986 ) arrived brand new, but within a few minutes of taking them out and proudly listening to them, I heard something wrong with the right side.
You know that sound of a hair rattling on a diaphragm? If you aren’t familiar with the sound, it was like a grand piano with coin on it that would rattle when you hit a sharp bass note.
I tried a few harmless ways of getting the hair out, but they build these things like a safe: Nothing was coming out of there. Not to mention I never actually saw anything in there and was only assuming it was a hair (you should've heard the seller, "I find it difficult to believe there's a hair in your HD800s, but if you really think there’s a problem......" hahaha).
And so it took me a whole week of listening and tinkering in vain before I picked up the courage to send the headphones back overseas for warranty. but naturally not before I had chipped the paint (arrgh!)
Ironically, when they got back one long month later, the paint chip was a comforting way to see I'd got my original pair back.
Now here’s the interesting part: The headphones were repaired nicely, no rattling when I got them back. However the left channel was louder then the right. It was like the whole soundstage was shifted to the left with some minor sound differences to boot. This gave me a little scare, but I thought; they may have changed the entire right driver which would mean the left side has an extra weeks burn in (right?).
So I unplugged the left side and ran music through the right side for a few hours, low and behold the soundstage balanced up nicely after that.
I guess what it taught me is that no two drivers are the same. not even the two in your own headphones.
I'm also very curious to know if the FR chart I just ordered from the Sennheiser site will be accurate to my actual headphones and not to my SN, if that makes sense.
P.S. I never got to see that small hair that cost me $100 postage...