3 Subwoofer hook-up question??

[Big Daddy]

Problems Associated With One Subwoofer
With some care in placement of a single subwoofer and the listening location, one listener can experience fairly smooth and deep bass in a rectangular room. Unfortunately, other listeners seated elsewhere in the same room will hear different bass response, which may be significantly irregular. Trying to reduce some of the largest peaks (too much bass) at one or two frequencies is possible with careful placement and equalization for one location and one listener. But attempting to apply equalization for multiple locations is usually ineffective. There are far too many problems in a small home theater room that cannot be solved with one subwoofer.

In most circumstances two subwoofers will perform better than one. While you might assume this is for added SPL, the greatest benefit will actually be smoother bass response. Using two subwoofers is preferable as you will get a better bass performance and will have less of a problem with standing waves, since the bass will originate from two locations. Two subwoofers are easier to place and result in a flatter frequency response and creation of a much larger “sweet spot” for everyone in the room to hear smoother and more consistent bass.

Use An Even Number of Subwoofers
Two or four subwoofers deliver the greatest benefits in smoothing out irregular bass for multiple listening seats. According to Todd Welti at Harmon International, whose white paper, "Subwoofers: Optimum Number and Locations," explored in detail multiple subwoofer performance: “The conclusion I came to was that two subwoofers give you about 90% of the performance that is possible, and that four take you about as far as you can reasonably expect to go. Anything more than four is not going to get you much in the general sense -- and these are general conclusions.”

Please read the explanation for multiple subwoofers in the two threads on subwoofers, particularly the second one. They have sticky under Speaker Discussion. A Guide to Subwoofers, Part II.