I just noticed that my sub has a dial where you can select the crossover frequency. It ranges from 60~200Hz. I have a pair of Paradigm Mini Monitors for mains. Where should I set the crossover. Doesn't THX suggest 80Hz. It also has a selection for choosing the crossover slope(12dB or 24dB). I would appreciate any suggestion about the proper settings. Are there proper settings or is it a matter of what sounds best to your ear? Thanks.