This can get quite complicated. You can send the signal into the sub, use its crossover so that it sends the rest of the signal (all frequencies above whatever you set the sub's cross-over at) to the mains, and set up your processor so that it thinks there's no sub. Most processors send the LFE effects to the mains when set up that way, so they'll go to the sub. You'll also get sub action when playing CD in 2 channel. There's a couple of annoyances with doing it this way, though. You'll probably want to use different crossover points for music and HT, as LFE effects can get up to 100 or 120 hz. Second, I've heard that sub, and I gotta throw my two cents in here - it would be a crying shame IMO to have it producing base in frequencies that the martin logan's could. those are much better speakers than the klipsch. Third, and perhaps most importantly, inserting the sub in the signal path from the main amp to the speakers will almost always degrade the sound quality.
Most surround processors have a built-in crossover, such that whatever the source is (DVD, CD, satellite, whatever), you can select a frequency, below which the signal is sent to the sub. With some processors it just sends the frequencies above the crossover to the speakers, however with some processors you can decide whether you want that or to have the entire signal to the speakers. Running them 'large' means they will sound the same as they always did, and the sub will be an addition at the lower frequencies. Running them 'small' means they produce the frequencies above the crossover, the sub produces the frequencies below it.
However, if you'd like to do it the other way, it will work.
Most surround processors have a built-in crossover, such that whatever the source is (DVD, CD, satellite, whatever), you can select a frequency, below which the signal is sent to the sub. With some processors it just sends the frequencies above the crossover to the speakers, however with some processors you can decide whether you want that or to have the entire signal to the speakers. Running them 'large' means they will sound the same as they always did, and the sub will be an addition at the lower frequencies. Running them 'small' means they produce the frequencies above the crossover, the sub produces the frequencies below it.
However, if you'd like to do it the other way, it will work.