All speaker drivers, as well as the internal wiring and crossover parts need at least 100 hours of usage before they reach 90-99% performance level. Especially the driver suspensions need to be loosened up in order to move in and out rapidly and uniformly. I've owned over 20 pair of new speakers in the past 15 years, designed and built even more, and all have sounded worse then a broken in set of demo speakers, and did not have the proper low frequency weight or high frequency speed, delicacy or extension until about 100 hours or more. Also, the wiring, resistors, and film capacitors need to be "burned-in". As far as the effects of old age on drivers, as long as the surround around the edge of the cone is not foam, (deteriorates rapidly), cloth or butyl rubber will last and remain consistent in performance indefinitely. The spiders surrounding the motor/voice coil also tend to hold up indefinitely in my experience, however, they can wear out with heavy usage and allow the voice coils to be off-center, which is rare with high end audio gear/usuage.
Also, with use the driver and other mounting screws can become loosened and require tightening from time to time, which can also improve performance.
Also, with use the driver and other mounting screws can become loosened and require tightening from time to time, which can also improve performance.