amp not powered? need help plz

Well i checked the wire coming out of the reciever and only 2 volts are coming out, I hooked up the wire to another power source in my car and the amp turned on, but no sound, so i suspect the head unit is bad, its the only thing i can think of.

I had this exact same kind of thing happen with a customer's car a couple weeks ago.  Their head unit was not under warranty anymore and my solution was to tap in to the +12v accessory wire in the radio's harness.  I don't think anyone leaves their car with the key in the accessory position without the radio turned on, so I doubt you'll have to worry about killing the battery.  It's a quick and simple solution--just something to consider.  Keep in mind that this is the same wire that tells the head unit to turn on.  As a general precation, I recommend you don't connect more than one external amplifier turn-on using this method. Good luck!