I am adding 2 extra rear speakers in my jeep, I have some rca cables comming from the rear speaker pre-amp outputs from the back of my pioneer stereo. My plan which works beutifully is a dc-dc boost module bringing the cars 12v up to 20 for the main amplifier. The main amp is a 2x25 watt class d module I got from online which actually works suprisingly well, but this is what is going on... I have the modules laid out in the back of my car with the 12v line and ground line I am going to use. You need to keep in mind that both the module and the stereo are using single supplies, and so the rca ground is just connected to the entire cars ground, and sence the module is a single supply it too has the imput ground just connected to the entire cars ground through the modules negative powersupply pin. So when everything is connected and all grounds are grounded, I turned on the module and I herd a big pop out of I think all the speakers in the car (but I couldnt tell) and there was no audio, only when I took power off of the module did I hear audio even through the rear speaker I had hooked up, but it only lasted as long as the decoupling capacitors were charged. I messed around with it and found that even just having the modules input ground connected to the rca cables ground was enough to make the pop even though I shouldnt have to ground the input anyway because it is already grounded through the negative power because it is a single supply. if I do not connect the amplifier modules ground to anything and I connect the audio signal from the rca cables to the audio input on the module then I hear a tiny bit of music but ALOT of weird distortion. It sounds like one of these (the stereo or the amp module) are a dual supply, but I did a test connection and both the stereos audio ground and the amp modules audio ground are just the same darn thing! Meaning the car batteries negative. HOW CAN THIS NOT BE WORKING! ITS SO SIMPLE AND YET IT IS NOT WORKING! help?