I called Crutchfield and they said there is an amp in the xterra's and that the wire is to turn on the amplifier. I was not aware the xterra had a seperate amp. Does anyone know the wattage of the amp? I have an SE with the 6-disc changer. The guy at Crutchfield said he thought it might be 20 watts and should not cause a problem. I am skeptical about that cause my Kenwood puts out max 50W and Full Bandwidth Power 22W (not really sure what the diff is. That is what the manual says).