I'm looking at purchasing either dual SVS PB-2000 subs or a single PB-4000 sub. Which is better? The prices are similar, the PB-4000 is $300 more ($1,900 vs $1,600). This is for movie watching only and will be paired with a 7 channel SVS prime system. The living area is large and open floor plan, see attached layout. Total area is 973 SF with 8.5' ceilings. Cast your vote!