05 Jetta - Stock deck/ AftMkt Sub

I did an amp/sub install in an 05 Jetta, fully loaded. Connected the remote wire to the key ignition so the amp is always on while the car is running, indepentent of the deck, and the subs source is the rear speakers, highlevel inputs. The thing is, when the deck is off but the car is running, it sometimes will start a low hum that gets loud enough to blow the subs within about 2 seconds. Also, when the deck is off, but the car is runing, you can hear the revs of the car as a low rumble from the subs. Any clue? I was thinking find the stock remote wire (there should be one because all of the speakers in this car have individual amps) and hook that up to the car. While the deck is on everything seems fine. The other thing could be this. Maybe the amp, (sony explode) cant handle the stock amped high levels of the speaker wire. Maybe use a High level to Line level converter?

Definitely get a better LOC. The basic LOC in the amp is more than likely seeing "too hot" a signal coming into it. PAC, Scosche and others make a good LOC, same with Audio Control in the form of an LC6 + sub level control.Top Secret, I can tell you but then my wife will kill me.