Multiple subs can help. I had a system with a sub for the mains , center , surrounds and a dedicated sub for the lfe. Gary Reber at 'WIDESCREEN REVIEW" has been a great advocate of this configuration for years . The first few pages of each issue outlines each of his many theatres the magazine uses for references in reviewing products. I plan on adding 2 more Aerial sw 12 subs this year to my multichannel/ theatre .