I have an older, lower model 7-speaker Atlantic Technology set (350 series) , but do not have the subwoofer for that system and plan to replace my current subwoofer. The room is L-shaped with the main rectangle about 18 ft x 12 ft. The side rectangle is about 8 ft x 10 ft. The ceiling is about 10 ft. The 350 series has a recommended amp power of 50-150W, 4 ohms, and a sensitivity of 90 db. The subwoofer that was sold in the 350 series was 200 W, while the 642e SB is 300 W. Would the 642e SB be a good match for these speakers or over-powering? Another alternative is the 422 subwoofer with 225 W. Or are there advantages in having 2 of the model 422 subwoofers instead of one 642e SB? This will be a front projector home theater application. I will have a Pioneer elite VSX-74TXVi THX-select AV receiver with the calibration ability to eliminate subwoofer standing waves . Thanks for any advice that you can give me on this.