OK I thought we should start a new thread to debate the "break in" phenomenon...
Break in claims
For decades, audiophiles, hi-fi retailers, and reviewers have commented that a lot of audio components seem to change over time in terms of sonic characteristics. The largest differences are reported with loudspeakers. Specifically, changes after break in are typically said to smooth out the treble and extend the bass response. The degree of change can obviously vary from speaker to speaker, as can the break in time period. After 30-50 hours, most would say that the break in period has ended, meaning that the performance characteristics have stabilized and will not change much in the future. Break in changes are virtually always noted as positive in every way.
Skepticism
From what I gather, skeptics believe that there may be a common perception of break in, but that there is never an actual significant change in the performance of speakers over time. This strikes me as a very bold statement, as they take a theoretical standpoint, and make a judgement on all the loudspeakers and listeners in the world. Surely skeptics can concede that in all the world, there's at least one pair of loudspeakers that sounds different after the first 100 hours of use. The skeptics' reasoning? Lack of scientific data proving the phenomenon.
Correct me if I'm wrong, but here is what I see as the skeptics' argument: "break in" is perceived because either
a)Brain break in: listeners first hear the differences compared to their previous speakers, and over time they lose sensitivity to these differences. Thus, after a lot of listening, the new speakers sound like the old speakers, and listeners attribute this to break in.
b)Power of suggestion: listeners have read about break in, and expect to hear it themselves. Though there's no audible change, they hear a change because they believe in it.
Skeptical inference
If a) is true, and listeners are reacting to the differences from their previous speakers, then a purchase of new "warmer" speakers (speakers with less treble) would lead them to perceive a growing brightness to their new speakers after break in. In other words, after acclimating to the new speaker warmth, their brain would compensate over time, until the new speakers sounded almost as bright as the originals.
The only problem is that almost all people claiming to hear break in claim that the treble smooths or mellows, if anything. No one says: "after break in, my speakers got really bright, and the bass disappeared." It's a one-directional change. Additionally, it is absolutely not true that after sensitization, one no longer hears the differences from the previous set of speakers. My Paradigm Mini Monitors always sounded a bit bright, and my M22s will undoubtedly always give me a magnificent midrange, even perceptually.
As for Alan Lofft's comments from the old discussion linked by chessaroo: he noted that listening tests did not substantially change over time with "anchor" speakers. I concur, as long is it's after break in, which typically lasts a modest 25-50 hours. If the first couple weeks of user tests were slightly different in treble balance and bass, who would notice?
Lack of evidence
It's true that you don't see a lot of scientific research being conducted on break in. The reason is that it doesn't matter, as the effect, perceived or real, only lasts for the first few weeks of listening. If you really want evidence, just goto an audio showroom and see if you can compare firsthand, like I did inadvertently. More often than not, it's quite obvious.
-Cooper
