Your first question was easily answered by Tony, this second questions is a little more complex but it is usually recommended to set all speakers to small and run the xo around 80Hz.Good. That's what I did. I also set my fronts and rears the receiver to large. Does that make a difference for sound? I'm new to this aspect of home theater. I've always own HTIB.
What speakers, sub and receiver do you have?First, conventional wisdom is to "Let the sub(s) do what subs do - handle the deep bass and lessen the AVR's amp's load for increased headroom for the remainder of the FR.