I want to add a second subwoofer to my existing Home Theater system and wanted advice. My room dimensions are 20 x 20 with vaulted ceilings. I have one NHT SW12 behind my main speakers. I have read that I would have a significant amount of standing bass waves with the vaulted ceilings. Is it a waste of time/money to add a second SW12 behind my listening seat? Would it be to much? Any advice would be great!! Thanks a lot.

Regards,

Andy