My main speakers are Infinity IL-60's, which are powered towers. Now these are not just a speaker with a sub in it, they have the ability to cross over the signal to where it needs to
go. Even though they produce good bass, I am going to add a sub. The question is what is
the best way to integrate the whole set up.

I am using a pre/pro and separate amps. My first idea was to split the signal from
the pre/pro to the amp and the sub in the tower. I can set these speakers to large and
let the crossover in the speaker send the signal where it needs to go. This would allow
me to use the .1 channel just to my sub. The goal here is to have "full range" mains
while also using a sub. I can then set the cross over on the separate sub a little
lower, say in the 60hz range.

Overall I want a good smooth sound that will pound you when it needs to.