The headunit is a Alpine model 7894. The amp is a Pheonix Gold Qx300.1 mono. Both power and ground are 8 gauge wire. My ground is less than a foot long and is running to the rear seat mount. Power wire is fused less than a foot from the battery. None of my wires have been spliced, cut, or anything of the sort. I couldn't tell you what my remote wire is, it just came with the kit. RCAs are phoenix gold as well. The popping occurs whenever the amp shuts off. So it does it when the I turn the car off as well as when I turn the radio off. It cannot be the amp because it has done the same thing with both amps that I had hooked up, and this is the second set of subs I have had hooked up. So here is what I know:

1) It is not the headunit unless the noise is coming through the remote wire. The pop still occurs when I have the RCAs unplugged from the amp.
2) Its not the amp itself. The pop occured with both amps I have tried, and at different wattages.