Only speaking to your comment on the theoretical of 500 hours ... good design.
I would doubt break-in is a target for speakers... but what they sound like is after breakin. A minimum life of a decent speaker system is 20,000 to 30,000 hours withiout noticeable degradation... many can easily go much longer like over 50,000. 500 is not much. I can easily see it happen if the target is very tight sonic qualities then very ridged materials is what you would start with and those materials may take a long time to reach optimum pliability.

