Bad amp or HU?
 

I have a 2004 Monte Carlo SS with the 230 watt system option.
When the amp is cold I only have sound coming from the left rear speaker. But after the car has been running, the door speakers slowly start to work. With the amp unplugged I stil get the bass only. So does it mean that the head unit drives the rear bass speakers. So does it sound like the head unit or the amp is bad?

Den

I noticed that my stock rear bass speakers still play with both plugs removed from the stock amp.
so is it normal for the head unit to drive the rear bass speakers even when the amp is unplugged?

Thx, Dennis