marty, the nad's a hi-falutin digital amp which provides options for running either the sub full range or at different crossover frequencies--i would assume there's a crossover bypass switch on the hsu which one would use if he was setting the crossover at the amp, but i'm a dullard at such complexities. assuming the foregoing (including the dullard part), would it preferable to set the crossover at the amp or the sub?