Hi Wayne, I have a unqiue setup in that I have a sub ontop of another: - PSW650 stacked atop SVS 16-46PC in front left corner of living room (aprox 3' clearance from top of SVS to ceiling) -subs are aprox 12.5' from listening position (Onkyo 898 rcvr w/sub distance set to 12.5') - side firing dual polk 10" drivers are aprox 1' from corner walls (polk recommends no less than 6" clearance) - SVS downfiring driver is aprox +6" from corner walls - room measures 12w x 19l x 8.5h with center, fronts, and subs placed along the width dimension. -The 19L dimension opens up to a fair sized kitchen (the listening room is not enclosed) - built in variable filters on subs were turned off (ie, by-passed) - my toshiba DVD player could not play test tracks greater than 98, was unable to access Hz tones greater than 98 - AutoSound Test CD#102 tracks 10-98 sine waves, these tracks were not recorded in full scale, ie, 0 dB) - Subs were INDIVDUALLY set-up/calibrated to 78dB (read 75 on the RS meter) as follows: A. the rcvr's Sub-Out (LFE) test tone was used for setting each sub to approx 78db w/ LFE=YES (ON) - B. the rcvr's LFE level was set at it's min setting of -15dB and the rcvr volume dial was set at 75 (ie, -10dB note: 100=0dB reference) C. each sub's volume dial was adjusted so that the RS SPL reading was aprox 75dB for each (he other sub was turned off). The SVS vol dial was turned up aprox 3/4 D. ALL spkr channels were turned off E. both subs were connected to the rcvr's LFE out via Monster RCA cables (18' lengths) and Monster RCA 'y' splitter cable I'll put my data on the next post . . .