Have I shown that break-in exists? No. I wish I could say the slowly descending IMD products is clear evidence ... but it's not. Who knows what that measurement represents. I do think, however, that if break-in is measurable, it would be this type of measurement that would show it. I'm pretty happy something showed up at all.
Have I shown that break-in doesn't exist and is not measurable? No. The slight changes around 9kHz on the CSD plots, and the significant change in IMD products over time do indicate that something is happening, and happening in a way that seems to me to be properly indicative of the things I've heard with break-in effects. I think the nay-sayers need to acknowledge something might be happening here.
The one thing I think I have proved, however, is that if
break-in does exist, it is not a large effect.
When people talk about night and day changes in headphones with break-in, they are exaggerating. This data clearly shows that the AKG Q701 --- a headphone widely believed to change markedly with break-in --- does not change much much over time.
My hiking boots break-in; my sneakers break-in, too. But my hiking boots aren't going to turn into sneakers over time. This idea that you simply must let headphones break-in before you know what they are going to sound like is a myth. And this data busts it.
I think there's a little more to the story, though.
Music is made of a multitude of frequencies. When the entire spectrum of music suffers from intermodulation distortion producing a sea of IMD products some 60dB down, I suspect it can be clearly audible. Reducing the level of this background crud 1 or 2 dB might certainly effect the subjective experience. I think it's extremely important to recognize that the perceptions of my measurement system in objective metrics may be on a completely different scale than that of the observer in the subjective experience.
How can you measure beauty?
The difference between a very good violin player and a truly great player is not objectively large. The devil is in the details; it's small subtleties that separate the two. So while the objectively measurable difference between the two players might be small, it may make the difference between an ecstatic and a merely pleasant listening experience to the human observer.
So, while headphones change little over time, their ability to deliver pleasure may improve markedly. Easily hearing the differences I've so often heard before
13 out of 15 times in a simple blind test proved to me this is a subtle, but important distinction.
