No, it just helps even out the room response.
I don't really understand. If you set your crossover to 80Hz, won't the sub take care of all the frequencies below that? In that case, your mains will not play anything below that so any bass you'll have in your room will come from the sub. Am I missing something?
To reinforce my position, in that case, neither the 60s or the 80s will play anything below 80Hz and since their freq response is very similar above that I still don't understand why people have the 80s over the 60s if it's to use with a sub.
bdpf,
It's more of a gradual slope than a definitive cut off, so you are still hearing a combo of the speaker blended with the sub. In most cases, the leading edge of the sound may start with the M80 and then move onto the sub. And, like others have posted, you don't have to use 80Hz as a cut off, you can adjust to what sounds best to you.
As far as using the sub to even out the sound, you can place the sub(s) in more advantageous positions in the room, thus negating room nodes that you may not be able to get away from with the placement of the towers.
