As my old professor once told me, 'Fact' is only a convenient way of saying 'here is what most of us believe in.' Things are constantly being proved and unproved all the time. Even scientific proven 'fact' can turn out to be fake but still attracts millions of believers.
You can record the before and after sound of a K701, but there will be those who do hear the difference, and there will be those who don't. You can probably measure the smallest fraction of the difference b/w the before and after sound on a machine, but it certainly doesn't mean you ear will hear the difference, nor does it mean others will/can hear any difference. After all, how can anyone objectively measure the sound quality* of an headphone, which basically is a subjective construct to begin with?
We all have different sensitivity of hearing, and we all hear our world slightly different from another person. While you might be able to pickup a -0.5dB over 16Khz and claims that burn in exists, I probably won't hear any change on that range. While you can claims the effect is real as showed on measurement, I could just as well argue that the small change mean nothing to me and burn in is a fake.
In the end, there is no absolute 'fact' even in the world of science. In fact, a good scientist should always question the fact, as this has happened more than you can imagine: the same data can be interpreted differently by two schools of scientists. The same professor also once said, data don't tell us the fact, we are the one that interpreted the 'fact' based on what we believe those data has shown us.
*as the goal of burn in is basically trying to change the SQ of headphone.
I like new opportunities for profit.
