There are two ways to fix this. One, does your amp have speaker level or high level input. If so you can hook the rear speaker wires into these inputs for signal and then run your remote from the power antenna wire.

Another way to solve this is by getting what is called a line level adaptor. We sell them at Crutchfield. The part # is 101PL2. This piece still requires you to hook your speaker wires from your deck to the adaptor. In any case you don't use RCA cables your signal comes from the speaker wire. The adaptor sells for $29.99.