Surrounds and spiders "break-in", Crossover caps "burn-in" and the better the caps- the longer they take. I've got an old receiver that I hook up to my system(tape out to a line level system input) for burning in components/cables/interconnects. I just tune the FM to a local rap station, face the speakers toward one another(one out of phase) and let 'er rip. After hearing that crap in the background for a few hours, ANYTHING I play sounds better!!