Maybe break in period is not the best way to say it, I dont believe they require a break in period per say just that the bass ( and maybe to a lesser extent the treble ) will improve i.e. less harsh and more smooth after the cones get a few miles on them, as far as the actual time, everyone has there opinion, i was told about 50 hours, reguardless, i have well over 50 hours now, and they do sound better now then when they were brand new, smoother treble and slightly better,more extended bass, thanks for listening!