#81: Everybody (me too) is biased all day, every day, for so many reasons, in so many fields.
But then again, headphones can be "special", and stuff really happens.
Years ago, a Hi-Fi shop in Berlin: I tried a headphone, one channel sounded a bit "thin" to me (don't remember make/model any more, I didn't buy it, not important anyway, no cheapo). I consulted the salesman, he verified it and then pressed hard on the pad, which made a click, after this the "thin" channel went back to normal. So the pad was just a bit off, not visible from the outside. His comment: Happens with most from time to time. Oh well... What if it happens with drivers too?
I would really like to know, how consistent the production of those headphone drivers is, this is partly still a case of "manufacture", not the fully automatic production as in case of chips and such. These are small, fullband drivers and many things can go wrong, really.