Originally Posted by a6walter1

That was definitely the issue. I measured the output voltage on the RCA lines and it would indeed surpass the 8V mark. As for settings, I have the accubass level turned all the way down, and the accubass threshold (little white adjustment screw between the RCA outs) all the way counter-clockwise. This ensures that the LC2i doesnt mess with the Z's signal since it does not get rolled-off like some other cars do. As for the wiring of the sub-level speaker wire to the input of the LC2i, I found that splitting the one channel into two and wiring them both to the LC2i gave me the best signal. IIRC the Purple wire is negative. Finally, the main knob and the bass knob. I have the main output turned all the way down since i am not using it and i have the bass knob (which controls the gain of the output signal) turned up approx 1/8 the way from the lowest setting. This seemed to give me the best results with my particular amp and sub combo.

Rockford Fosgate P3D4-10
Rockford Fosgate R500-1D