Interference
 

My old stock deck died a few months ago, and I replaced it with an Eclipse head. When I turn the car on I get a bit of static interference through the speakers, and they make a pop sound, but only when the deck first powers up. Is this cause by my amp? The old deck did this too, and I just attributed it to it dying, but it still does it.

Would adding a new ground straight from the stereo ground to the chassis help at all?

sometimes when you run the power wire next to the speaker wire, static is built, I used to have that happen in my previous cars so i learned to separate them from each other.
not sure if that'll help your situation but worth a shot if it's an easy task