I have my speakers calibrated to 75db and my sub is calibrated to 83db or so. My main L/R speakers are set to small. According to my manual, my unit directs signals that are 90hz and below to the subwoofer when those speakers are set to small. If that's the case, what (in theory anyway) is the preferred crossover setting? 90hz? 80hz? My mind is spinning reading all of the crossover threads, but I'm getting the impression that most prefer 80hz. Given the facts above, would 80hz still be preferable (again, in theory)? Also, does changing the crossover at any given time affect the amount of db's the sub is calibrated to? Thanks in advance for your replies!