Before I room eq'ed my subwoofers, I had much smoother response with the mains running full range along with my subwoofers. The more speakers producing bass frequencies in different spots the smoother the response in many cases but that is of course most noticeable in the upper bass as my mains don't have the same authority as my subs down lower, like say 50hz and down. Now that I've eq'ed the subs, I'm finding much less of an improvement running my mains full range vs crossed over at 80hz. I was just experimenting with that yesterday, going back and forth between 80hz on the mains vs full range. In fact, it may actually be better now with the mains at 80hz, but it wasn't before the subs were eq'ed.