I see your point. However, like all things with senses it is all very "touchy feely" and subjective. What one finds of taste another does not and to me, science does not explain all. Even if you told me the composition of tomato soup, be it ingredients or chemicals, one simply does not "taste" all of it to experience it.
So taste, let's say, an organic vs. conventional tomato soup under controlled terms and let's see if you can taste a difference. That's science in my book.
I'm not surprised if you couldn't when the measured ingredients are not much different (assuming we can measure ingredients responsible for taste).
I may taste what you do not, or you may hear what I do not. As easily as it is written that the changes "could" have been attributted to "environmental differences, heating up, earpad compression" etc, can it be definitively proven any more that it was any of those than it can that it was none of them?
Unless you repeat the test with a thermometer, additional microphone to record the noise produced by trucks driving by (which he said caused some of the tiny measured differences) ... no.
But even if those seemingly random changes were the effects of break-in, they were too small and didn't match what people reported ... and still report like parrots.
Besides positional changes, there are old vs new ear-pad measurements and the changes were enormous compared to anything you can find in break-in tests. If you do a 1000 hour test you'd think that the earpads maybe get flattened a little tiny bit.
All of this points to: whatever people are hearing, it doesn't seem to be the drivers breaking in.
I do not claim to know why or even if burn in is true of earphones and canalphones of various types. Yet, while acknowledging with high regard for the accoustical differencs in insertion for in ear monitors you speak of, I need no further hypothesis than that from which I have drawn my own conclusions. Healthy skepticism and experimentation.
Shure doesn't advice burn-in. They measured in-ears and microphones over more than a decade with the obvious result: no change of sound due to use. And their mics have bigger transducers than their in-ears.
You mention healthy skepticism but how do you eliminate bias and all kinds of external influence on what you perceived? Why does "I heard a change" mean "the driver must have been burnt-in"? Taking all the stuff from above in account I don't see the connection.
In neither case have I ever played said earphone for more than 6 hours prior to burning in. To me lessening the likelyhood of accuostic familiarization so to speak. I was as skeptical as you are and with good reason, as you yourself have. However in my "experience" of my own exploration of the topic, my previous post outlines what I found to be true.
I do not think that, Tyll's testing was flawed. However I find this subject in similar fashion to the way we measure Scoville units. On one hand there is high-performance liquid chromatography, the objective test (attempts to measure capsaicin content) , and on the other the Scoville organoleptic test, the subjective test (panel of tasters).
The real conundrum to me is, how exactly does one create and execute a test to measure the "sense" side of sensory experiences? You can tell me how many BTU a grille releases, but can you measure the sensation of how "hot" it is if burned by it? To me, this is what is proposed in measuring what someone what actually "hears" vs what sound(s) are reproduced.
Two things here: First, you can measure certain things more accurately than any subjective test will tell you. Can you "taste" or rather feel the difference between 850k and 900k scoville and reliably tell the difference?
Secondly, the real problem with headphones doing a comparison is that you need a perfect copy which doesn't exist. Even two headphones from the same batch will sound more differently (in some cases shockingly so) than doing 1000 hours of break-in...
Break-in just seems like a colossal waste of time, or at least a pointless exercise. That's what I
have to conclude from all the information I have.
