Just finished installing a 4 channel amp (already had a sub installed via RCA's) and there is no whine noise when the key is in accessory but when you put it in the "pre start" / when the car is running there is a whine through all the speakers and sub. I don't believe it's alternator whine since it happens when the engine isn't running and it doesn't go up and down in pitch when accelerating/decelerating. What would cause it to start whining when in the key is in the pre start position. To give an idea of noise level if the unit is above level 8-10 then you really can't hear it.

Probably picking up the fuel pump prime

Wouldnt the noise go away though once the fuel pump has gotten the system up to pressure

Its not the fuel pump i pulled the fuse and relay, same noise. I think i got a bad amp or the amp is crap to begin with...it is a mb quart onx4.60. Ive tried all i can think of. Moved the rcas temp to middle of car so no wires by them, different grounds for the amp, new ground for the headunit, one amp on one off vice versa to see if interference between them i have no idea where the sound comes from when in prestart and not acc whch makes me think twice about problems with any of the equipment

Does the amp make the noise if the RCAs are disconnected?