Let's use a configuration scenario to help explain how the triple cross-over
function works.

Settings:

All speakers set to small. (A Large setting by-passes the cross-over
function for that speaker)

Front: 40Hz
Center: 80Hz
Surrounds: 100Hz
Sub: ON

In this configuration the sub will see the entire LFE or ".1" signal. It
will also receive any signal below 40Hz from the front speakers, any signal
below 80Hz from the center channel and any signal below 100Hz from the
surrounds.