I had a Mirage OM-200 sub that died. I replaced it with a HSU STF-2. These measurements are across both subs. The sub in both cases is doing it's job (HSU is MUCH better on the low end) in the 80 to 120 Hz. range. Letting the sub handle the 80 to 120 Hz. range solves the problem except that a 120Hz. XO makes the sub locatable in the room.
I really doubt that this is a room issue. For starters it has manifested in two completely different rooms. Secondly, the Audyssey calibration is designed to offset room null problems. Thirdly, the Room EQ Wizard I've used in the new house clearly shows this issue even away from the main listening position. Finally, small differences in distance causing large amplitude changes (standing waves) is way more of a problem at 20-40Hz. than it is at 80-100Hz. and I'm not seeing any issues on the low end in either room.
