I believe that I can run the sub out of one of my amp's pre-outs.
--
Yes, it's a active subwoofer, as in it has a built in amplifier. Line level input is fine.
--
Will this still allow the M-60's to run full-range when the sub is powered-up, or will the sub take over and limit the low-end response of the 60's?
--
If you hook up the sub from your pre, the towers will still be running full-range.
--
Are there options or better ways to hook up the sub, other than going through the pre-out on the amp?
--
Yes, you can connect the speaker outs into the sub (instead of line level from the pre), then connect your speakers to the sub pre -> sub -> speakers.
Using the sub's XO, you can adjust the frequencies that will be handled by the sub instead of the speakers.
Different, yes. Better, depends.
--
With a sub added to my system, will the low-end still sound balanced, as opposed to coming from a focal point based on the subs location (i.e., corner of the room)?
--
Not supposed to, as the sounds coming out of a sub is not SUPPOSED to be directional; but just as speakers can sound boxy, so can a sub.
As far as if the sub will overwhelm the speakers, well it depends on how you tune/tweak/place them
