your amp turn on is hooked up to a wire that shuts off when the door is opened..... change amp turn on wire and that will solve your issue.it's a hafe note of base
a similar sound would be if a stock radio was playing just base and u really quickly connected the subs and disconnected them
it's not when I turn it off its when I open the doorsTo make sure I understand, you sub starts to go WUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUB when you turn off the car completely correct?
This is what happens when your sub is still on and connected to a LOC and doesn't turn off when the rest of your stereo does.
I connected my remote to my cig lighter port and it works gloriously.