Douglas_schroeder, "To date I have had no one, professional or amateur, contest my findings. I also have found no one who has replicated the test. I suggest those who doubt my little test, who ardently belive in Burn In, get double components and do the informal testing. I can tell you what will happen; you'll not be able to hear the difference. :)"
Well, apart from Geoffkait, I will also contest your findings.
However, before going into that, I will say that the phenomena of the listener "breaking in" to the component is just as real. I myself often notice this during parts analysis, which normally devolves into a mind numbing game of waiting. Our ears surely adapt to whatever's in front of us. I absolutely believe that explains a lot of why people live comfortably with their systems, only to have another listener come away mortified after spending time with it. As both you and Al stated, perhaps the most efficacious means toward countering this remains A/B testing.
The concept of break in parallels things like wearing in a new pair of leather shoes or blue jeans. There's a period where things undergo change; the before and after states behave differently in some sort of way(s).
A few quick anecdotes:
1) Working as a chemist / material science engineer during my 20s at a company that made high technology electronic materials, I performed many experiments on the conductor, resistor, and dielectric materials we produced for the likes of NHK, Vishay, Dale, Sfernice, Roederstein, Mallory, Panasonic, Sanyo, General Motors, etc. Proving the concept of break in to a degree orders of magnitude above irrefutable, the electrical characteristics of these materials do change in large measure during the early part of their lifetime, reaching a plateau of stable operation over what's normally/hopefully a long time prior to entering their phase of age or environmental related degradation
2) A definitive objectivist, Bud Fried, who normally spent about a third of the year in Europe, and influenced a fair amount of the work at companies like Audax, Dynaudio, Focal, Kef, and ScanSpeak from the 1960s through 1990s often recounted the research and development that went on. Practical use of a new driver would produce measurable and sometimes significant change in characteristics such as Cms, Qms/Qts, and xMax
3) A friend of mine whose business is rebuilding loudspeaker drivers often tells me about how the suspension (both surround and spider) changes. He's more of the type who would never measure this sort of thing empirically, but the spider in particular offers a visual and tactile contrast one can discern
4) Some time ago, I found a coupling capacitor shootout on the web. While there are more than enough of these out there, what made this one interesting was something due to the same sort of break in argument among the folks contributing there. Perhaps to satisfy his own curiosity, the gentleman conducting the test decided to run a PC based plotting measurement on one of the caps before (new) and after some run in to see if anything along the lines of "break in" could be detected. He wound up more than surprised at the obvious degree of difference
5) To your specific challenge, I have built several DynaKit ST70 amplifiers. After completing the new unit and confirming the typical measurements, I'll replace one I've been using for a while in that system with the new amp. Though the parts are normally (though sometimes, they're not) exactly the same, the sonic differences are always both obvious and predictable. It takes a good three to four weeks of playing most days for at least a few hours for the new amplifier to catch up to an older one. The same is true, though to a lesser extent both in terms of time and sonics when I go about evaluating parts like resistors and coupling capacitors in an already established unit.
The subject of break in tracks much like cabling. Even today I meet so many audiophiles who maintain that "wire's just wire." I begrudge them not. Likewise, should you continue to go forth feeling that same way about break-in, I understand.
