I have a pioneer 5 channel amp installed and when I have the music turned up to 9 or less it sounds perfect, crisp and clear. Once I get up to 10 or past I get a hissing sound. My stereo goes up to 60 but starts hissing at 10. I tried turning down the gains and that does not work. It still hisses weather I just lay music with the car on or off . I have my ground goes my to a bolt under my seat away from all other electrical. I used a grinder to grind the paint away to make it a good ground. Power wire is run on opposit side of vehicle from other amp wires but it only does it when it gets past 10. Any time read or suggestions ?