I just replaced by sub amp with an amp that puts out double the power. To take advantage of this new power, and match the amps, I turned up my door speaker amp's level input to ¾ of a turn. A full turn is the max setting. Now I can faintly hear some white noise in the speakers when the car is off. I really don't know what DB level it is so I'll try to describe the noise level. If I leave the car off, empeg on pause and the windows and doors open I can barely hear the noise while standing at the front right or left of the car. If I walk to the center of the hood I can no longer hear it. Sitting in the car I can hear it when the car is not running and the volume is at a fairly low level.

After doing some investigation it looks like the noise is generated by the amp. The only other source might be the power line. Going to check that tonight.

Am I being too picky? Do all amps put out this type of noise?

The amps involved are:

Sub - US Acoustics USG3000D - 400 Watts x 1ch @ 4 ohms
Door - US Acoustics USG4080 - 50 Watts x 4ch @ 4ohms