2001 toyota corolla S, Wierd noise

Wierd noise issos, please help with suggestions, if you have worked on the car or not. Using the factory radio, with the remote tied into a switched ign source from steering coloum. Using an intefire ammp Used the interfires high level input, I believe this car has a factory amp but unsure, used the 2 rear speakers to tie into the amp.     made weire humming noise when the car was started or when the radio was shut off.    Thought is was a gain issue, so turned them down and it went away. Well the customer comes back today, and I thought well maybe the High lever from the amp just cant take the level from the amped speakers, so I used a Tsunami HI-Lo converter,   all was fine. Then we shut the trunk, and this is where it gets weird, it only makes the noise during startup and when the radio is off, when the trunk is closed. When the trunk is open there is no problem. I tried regrounding in 3 spots in the trunk to no avail, so I re grounded to the lower bolts on the rear seats, that didnt work either,   what gives?    It only makes noise when the trunk is shut. Someone help me out here!2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

no, do you think that would help instead of the switched IGN wire?2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place