I just recently got myself an HSU VTF-3 MK2 and absolutely love it. I am now trying to integrate it into my HT and with my older subwoofer, an HSU STF-2. I spent the better part of my evening last night trying all kinds of different things to get the smoothest possible 1/6th octave frequency curve. I've tried different crossovers on my AVR (Yamaha RX-V2400): 60 Hz, 80 Hz, and 90 Hz. I've tried both subs in phase at 0, out-of-phase STF-2 at 0 and VTF-3 at 180. I've tried a couple of different locations for the VTF-3. All my attempts always resulted in a slightly smooth curve, but there was always a problem at some frequencies. Particularly, when the two subs are in phase, I have a 20dB dip at 56 Hz. When they're out of phase, I have a smoother curve, but its overall level seems weaker from 16-36 Hz. My front speakers are JBL S310II capable of going down to 37Hz (-3 dB), and I've tried setting the Bass Out on my AVR to SWFR as well as BOTH (although they're set to SMALL, the BOTH setting still sends some bass to the fronts). Here is a diagram of my room, with possible locations for the two subwoofers: I've tried the diagonally opposite location of the two subs as depicted above in orange, but I've not yet tried the configuration in green. I've also tried with the STF-2 in the front left corner (orange) while the VTF-3 was in the rear center (purple). Unfortunately, putting the VTF-3 MK2 in the front is not an option because wall A is shared with my neighbor of our semi-detached houses and the VTF-3 is too powerful and disturbs her a whole lot. Wall dimensions are as such: wall A is 14 ft. wide and wall B is 23 ft. long. From looking at the room diagram, can anyone help me out? Would the diagonally opposite configuration in green work better than the one in orange? I think sticking the VTF-3 MK2 deeper into the corner as in the green configuration might work better than the orange configuration which sits the VTF-3 far from a corner. Is it worth trying? Or can anyone suggest any other configurations?