How much Break-In Time for speakers?

For loudspeakers, the recommended break-in time is around 35-40 hours using regular music or movie source material at normal playback levels.

During this period, there are slight changes to the Thiele/Small (T/S) parameters of the drivers and the electrical properties of the crossover network. While sophisticated equipment can measure these changes, they are typically not audible. A loudspeaker should maintain stable electro-mechanical properties after the break-in period and remain consistent for many years.

Break-in for subwoofers is hardly necessary, just make sure the sub is setup and tuned properly with the loudspeakers.

The primary purpose of the break-in period is to allow the listener to become accustomed to the sound of the new speaker. Due to auditory recency bias, new sound equipment is often not perceived as better initially. By listening exclusively to the new loudspeaker for a few weeks, users will forget the auditory memory of their previous speaker and adjust to the new one. Only after this acclimation period can listeners start forming meaningful subjective impressions of the new loudspeaker.