B&W Drivers should need only a few minutes or maximum of a few hours. If it still sounds different after a week then your old drivers may have been damaged/over driven or something is wrong (for example did you make sure that the seal is airtight around the new drivers that you installed?).
I'd stay away from suspect products that claim extremely extensive break-in periods, as this is indicative of poor design, poor choice of unstable materials or poor manufacturing tolerances. The parts that most flex in a good driver (surround and spider) are specifically designed to have as minimal effect as possible on the sound you hear.
I'd stay away from suspect products that claim extremely extensive break-in periods, as this is indicative of poor design, poor choice of unstable materials or poor manufacturing tolerances. The parts that most flex in a good driver (surround and spider) are specifically designed to have as minimal effect as possible on the sound you hear.