But seriously. I don't claim that it DOESN'T exist, just not to the degree that yourself or any others claim it to. And considering that you believe that you have experienced burn-in means that you do believe it does exist. Which means it would be that much harder to convince you since you'll always go back to "Well that headphone wasn't the PX100." Thus always solidifying the claim in your head. In fact I could probably go through the list of headphones that I tested DBX for burn in and get the same reaction.
I think we are just arguing for the sake of arguing at this point. Gotta love the internet.
I think our viewpoints are not that far apart. I'm not 100% convinced that burn in is real...even after my little PX100 experiment. On the other hand, my little experiment leads me to believe that things are not as clear as some would claim. Even Tyll's measurements show that things are not as clear as a certain fellow would like us to believe.
But think about this. In my PX100 post I mentioned that I heard a difference and suddenly I'm bombarded with "bias" and "expectation"...and I'm told that I'm imagining things and that there is no way in hell the two headphones could have sounded different. I'm told that what I'm hearing is wrong...because someone else has not heard any burn in changes...and they are right. I'm wrong because they are right. Okey-dokey.
The truth is that nobody is really sure, not even Tyll.