Ground question (Sorry)

 I eliminated alot of ground noise when I sanded the ground spot to the bare metal where my amp is.   But my question is If my deck isnt grounded properly, would i get ground noise in my speakers even if the amp wasnt hooked up?  

Are you grounding your HU to the chassis separately, or through a aftermarket wiring harness?

If you drilled and tapped your own hole, from the BLK wire on the HU's cable, then the tap spot should be sanded and screwed down tight.

If you used the aftermarket harness, then the ground should be the same ground as your stock HU, and would be grounded well enough.

If you doubt the connection, you can always use the aftermarked harness, but ground it yourself.

DXAV

if your HU isnt all that great you'll hear noise without an amp.
if RCA's arent protected well enough and or not seperated from power/ground wires, they can recieve noise from those wires.

i would ground my amp back to the battery, thats from my own experiance though. it not only reduced some of the noise, my speakers can go louder than they were able to before. just something to consider. i would check how well your ground is with a multimeter, it should roughly be .5 ohm's i think.