New speakers are like a new pair of jeans - the material in the surrounds and spiders are stiff and need to loosen up with wear. No magic, just materials science. Paper surrounds requires more break-in than butyl rubber, foam is in between. Down the road, foam typically disintegrates first, then paper, and finally butyl rubber. A lot also depends on the environment. Light, especially UV is death to foam. Humidity, too high or too low causes problems with paper. Heat causes its own set of problems, especially with electrolytic crossover caps. So when you consider all the variables, there are lots of reasons why speakers vary in break-in and also break-down.
Okay, How Important Is Speaker Break In? (Dynaudio Contour 60i)
I have been running 25+ year old B&W Matrix 803 S2 speakers in my 2-channel system for about 15 years, and I finally treated myself to new speakers. Mock me for buying based on research alone, but I got a really good deal and just unpacked my beautiful Dynaudio Contour 60i's. The Dyn's are not broken in, just starting to play around with different songs, but I am expecting an improvement out of the box, and not getting it. They are no more revealing, and slightly harder and more jangley in the mids and highs. The bass is of course much better with the big Dyns, but the B&Ws with the Dyn Sub6 subwoofer I was running were better. I have very good equipment so it is not a matter of driving bigger speakers (ARC Ref preamp and Bryston 7bSST2 monoblocks). Unless speakers get A LOT better with break in, I thinking these Dyns may be converted back into cash. Thoughts? Thanks.