I am installing a system into my 2011 Mazda 2 and I am getting what seems to me an odd voltage reading on my rca cable that will plug into my 4 channel amp. My amp can take high level inputs via the RCA input (only has RCA inputs and Pioneer includes a speaker wire to RCA adapter) so I cut the stock front speaker wires coming from the stock head unit, connected a run of 18ga speaker wire to them, then connected them to the Pioneer supplied RCA adapter. When i measured the RCA plugs with my voltmeter, I measured positive on the center pin and negative on the ring. The right channel read out at 3V but the left channel read out at 23V. I tested this with the car key turned to ON but not with the car running. I had the radio on a radio station that was just static. Is this normal? Seems wierd to me. Any idea?