Man, as hard as I tried not to believe in burn-in, the evidence just keeps slapping me in the face.
First, my 2nd 535 (the replacement) was far from clear sounding when I first received it (towards the end of April (or early May). By (say) July, it was getting better (in the clarity department). However, since I was having a problem with my Galaxy S2 phone, I wondered if it was the culprit.
Three weeks ago I received a new T-Mo' Galaxy S2 (under warranty) for the headphone jack (that I thought was defective), and Voila! 3D returned! The lead singer in the first song I played appeared to be located near the back of my throat with background singers slightly beyond my ears. Then the nozzle broke off my left-side earpiece just one week later. Shure sent me a new one (no questions asked—I LOVE their customer service). It was a 6 day turnaround.
Now I have a left side earpiece (new) to go with the right side (burned in for months). The left side sounds pretty bad. The lead singer imagining leans to the right now. The right side still sounds 3D and the left side does not. The right side sounds crisp and clear; the left's fuzzy and distant. I now leave it connected to a music player day and night (in the hopes the left side will catch up someday soon).
I've always been of the belief that if there was such a thing as “burn in”, the manufacturer would put it in the manual (if not conditioning it before selling it). The improvement is dramatic. If Ford sold a car that got 25 mpg initially, then 50 mpg after the first 1000 miles, surely they would advertise and brag about it. It's a feature worth talking about, right? Do they not know? Maybe I should start paying attention to cable talk as well, eh?