Yup, thats the wrong way to cut the RCA's. The RCA uses 2 wires for each channel, a + and a -. depending on the type of RCA you are using, the wires will be configured in one of a few ways. For a car, you should be using twisted pair RCA's. This means that the 2 conducters are twisted down the whole legnth of the RCA. When you strip the outer layer, you will be left with 2 wires. They will be insulated by different color insulation, and there are a lot of different combinations used. Commonly, black is usually negative, red is always positive, white will be the other of the 2. There are many RCA cables that will have a + center conducter and the - will be all around the + one. DO NOT use shielded RCA's. They are great at blocking RF interference (in a home) but are an antenna to electro-magnetic interference (in a car). I can't remember the pin-out of the crossfire radio, but if there is a left + and -, and a right + and -, connect them respectivly. If there is only a left +, a right +, and a common ground, connect the 2 - from the RCA cables to the ground.

The reason your amp is turning off is because it is going into protection mode when you plug in the RCA. The amp sees a short in the RCA input, so it turns it self off to prevent damage to anything.