Set the LFE to at least 120 Hz. That is the highest frequency that should be in that channel (the .1). This is not a crossover, but rather a filter.

Everything else your sub plays is determined by the crossovers. In your setup, anything sent to the rear speakers below 150 Hz will be redirected to the sub (this not a brick wall, some below 150 Hz will play in the surrounds). Same thing for your other speakers. Anything below the crossover is sent to the sub.

Also, there probably won't be much lower bass in the back speakers. As I said before, mine are at 120 Hz and I've never been able to localize my sub. I would assume that I would if it was producing 120 Hz tones.

Dave
Audyssey Setup Guide