Speaker break-in explained
There is an article in the Stereophile magazine Nov 2005 issue page 18 about the break-in period for loudspeakers. I could not find a link to the article. Maybe someone can help with a link or buy the magazine for complete info. I am only a subscriber to this very good magazine.
Briefly, it describes “stress softening” the rubber in the surround of the drivers. “The fastest way to break in a speaker’s bass driver is to ensure that it receives plenty of high-excursion, low frequency signals, in order to put proper stress on the surround.” It also talks about how the drive-unit cone and voice coil elements also improve during this process and creates balance in the entire speaker/cabinet design.
This is an interesting, detailed article that I found answered many questions on why a speaker slowly sounds better the longer it is played during break-in. It’s kind of technical but easy to understand.