the better the speaker and the more resolving the system is, the more this can be noticed, happens over the first 100 hrs at least... for mine, changes were noticeable up for 300-400 hrs...
this is significant... those who say no just don’t know...
One of my business partners would beg to differ having done extensive work on cone materials and cone breakup which required extensive testing of drivers to determine where parameters stabilized including high speed surface imaging and laser interferometry.
So have these new speakers and been told they need a hundred hours to be broken in, and then sound will improve.
This statement above is total crap. It does not take 100 hours to "sound good". There will be subtle changes after hours of reasonable volume. No magical major improvements after that. The only thing that happens by 100 hour is you got used to them.
w.r.t. Capacitors, electrolytics if they have been sitting can have a parameter change over a period of time, mainly in DC parameters, but you don't see those too much in high end speakers. Film capacitors are very stable ...it is why they are used. There are people who have equipment and can test these things to significant accuracy. They are not the people making the claims. We can't measure how humans will perceive change, but we can measure if there is change.