The JBL amp is in the trunk next to the subwoofer.
Word.
That is definitely NOT the amp.
So then maybe the xm transmitter? I'm thinking I should pull the seat to insure no damage was done...
You have given us no information. What stereo does your car have? What options? Was it bought new or used?
The government is watching you.
Toyota would not mount anything under the seat like that because there is a floor vent.
And damage to what....?
The only thing remotely close to that area is the passenger seat occupation sensor.