When setting a crossover to 80hz, and then using the sub for the LFE channel, are you missing the bass that would be going to the speakers that is below 80hz, or does the LFE channel include this? If this bass is being missed, would it be logical to use two subs, maybe one in the front left corner for the below 80hz material, and then one in the back right for the LFE? I know dual subs should usually be placed together, but if they are next to each other and one is doing the LFE and one is doing the below 80hz stuff, wouldn't it sound muddy? Also, wouldn't making the preamp send a signal to the sub that combines the LFE and below 80hz material make the sound coming from the subwoofer seem not very defined? Or is the below 80hz material that is being sent to the speakers not very important?