Pop sound from aftermarket subs after turning off

So I got the active LOC which is LC2i and tapped into subwoofers at the rear for signal. This specific LOC gives turn on signal for the amp which is why I got it but when I turn the car off it gives a annoying vibration from the subs. I was able to fix it by decreasing everything on the LOC. My question is what can be wrong at this point?

One more thing is that I have gotten and . How can I wire these at 1ohm I got two channels on my amp.