You know, the only way I've ever been able to justify this phenomenon to myself is that there are a number of moving parts inside the speaker. The voice coil, the diaphram, and the suspension all move. I always figured that if "break-in" was a real phenomenon it would have to be due to structural changes in those components induced by hours of play. (kinda like a wire bent back and forth enough times gets weak and brittle, or the texture of a sheet of paper changes notably if you crumple it and flatten it enough times.) I still don't buy it though, looking at how those components could physically "degrade" after hours of use just doesn't seem to add up to any difference that should be audible.
