I have been looking for a while, and am interested in building a sealed sub using the new Avalanche 15. To improve performance, I'm thinking of using an amp like the Rythmik 350 that has a built in LT circuit. My problem is this, when I model the LT circuit in WinISD Pro Alpha, I rapidly exceed the maximum excursion with all but the most minimal LT settings on the Rythmik amp. For example, if I choose an LT circuit with settings of 20hz and a Q of .7, a 300W signal is above 30mm excursion by about 22hz. If I choose an LT circuit with a setting of 20hz and a Q of .5 (F6 at 20hz, F3 at 30.5hz), a 300W signal is above 30mm excursion by 15hz. My results with the Tumult instead of the Avalanche are virtually identical. I'm confused? The amp doesn't seem particularly powerful, and the LT settings don't seem off the wall...the 14hz settings are completely useless, and the 28hz settings don't get me anywhere near what I'd hoped. I am starting with a box size to give a Q of .707. If I shrink the box size down to control the excursion (down to 40L or so), the transfer function, even with the LT circuit, goes right to poop. Am I doing something wrong?