I installed aftermarket head unit and I'm getting hiss on both the radio and Bluetooth or even native apps (android stereo). The lower the volume, the louder the hiss. I don't think this is a ground loop or engine noise because the hiss is always the same when driving only dependent on how high the volume is. Also I suspect it's the gain on the amp because it goes from volume 0 (mute) to like volume 40% the next step up. There's nothing between 0% and 40% so even if I didn't have hiss I need a way to edit the gain from the amp. I also tried bypassing the amp by removing the "remote amp" wire on my headunit, and then connect wires from it (the hu) directly to the speakers in the door. When I did this, the sound is MUCH MUCH lower and absolutely no hiss.
