Huzi

Hello Guys, I have a 2013 G37s Coupe with Bose and Navigation, I have tapped into the harness ( 23,24,25,26) I am using a AX-MLOC725 for my Line Output converter. For ground I am using a stud on the trunk floor near the Bose amp. I sanded it down and secured but I still get the whining sound that mimic the rpms. When I use the same ground for my amp which is connected to the subs. I don't hear anything from the subs. Even when the Amp is unplugged and the LOC is plugged in I still hear the whine and yes I have kept the power cable away from it.