All modern, powered, sealed subs have an analog phenomena called group delay (in the digital world this is often referred to as latency) so to best integrate sub(s) you must fix that timing issue so the sub lines up in time with the mains at the crossover frequency area. Since you cannot remove this inherent delay in the sub you must add this delay to all the top channels. The PHASE knob on a modern sub ADDS MORE delay to the sub than its intrinsic approximately 10 msec. IN A HOME THEATER SYSTEM you do this by manually setting the speaker distance settings in the setup menu. Since consumer equipment operates sort of backwards, when you increase the distance setting of the sub you are adding delay to all the other channels. (!) I suggest setting all the speaker distance settings THE SAME and to 7 feet; then add 12 feet to the SUB distance only (so the sub distance now = 19 feet). Now you have added a bit more than the correct amount of delay to the REST of the system (the L C R Ls Rs) so you can then properly use the PHASE KNOB on the sub to FINE TUNE the timing match. This will give you the best possible impulse response through the entire system; the imaging and focus should then should be uncanny, and the bass focused and as tight as possible. Again, if this is done correctly, even if the subs are behind you, you will NOT localize them; it will seem as if the bass is playing from the front of the room, where it belongs, and this is true even if the crossover frequency is as high as 120 Hz. Heres another audio non sequiter: people say that bass is non directional. This is completely wrong. Audio is more or less directional; the phrase should be bass is NON-LOCALIZABLE because the wavelengths are so much larger than your head and therefore there is no phase difference between your ears relative to the wavelength size. The higher you cross over, the more you MAY localize the bass IF the timing of the sub is so far off from the mains that it almost becomes a separate musical event in time. If the timing is correct you will feel the bass and localize on the harmonics.