What is the size of the room?
Have you tested your room for standing waves and whatnot? What are the existing room treatments?
I would almost always use two front subs, assuming the room allows it, but it all dictated by the space you have to use.
Considering a Second Subwoofer for the Front
I am considering a second sub. I have two bucket subs for the rear. My taste in music is classical to Enigma. The room is 14 by 22. The front sub is from Salk. The speaker is 12 inches. What considerations does one need before a decision. Thanks in advance, Steve