aur2mas

My amplifier is apparently a brand new pos. Wired up and no output, I've checked everything that I can think of and also three Crutchfield Techs. I can hook up a cell phone to the inputs with an adapter and the amplifier and sub play fine, but cant get anything out with the head unit rca wired in. I have already replaced the head unit thinking it was the pre-outs of the head unit, issue still looming. So what I have is with the amplifier powered down my load on the speaker output terminals is as expected, 2 ohms, when I turn the amplifier on the output load switches to 10.4 ohms. How could this happen?