Car Stereos: Soundstorm 1500 watt class D...maybe a bad ground?, amp circuitry, watt class

Question
Hello I own a Cadillac 92' deville and I have got 2 12" kickers L5 hooked up on soundstorm 1500 watt class D amp (though I have this problem with all my speakers, the issue is not speaker related) When I have the input turned quarter of the way down it makes regular noise, but when it is turned up more a makes a loud buzzing like a ground sound? How can I fix this, what is the problem?

Answer
Chris,  I would have two suggestions.  Is the ground close and tight?  How large is the power wire?  If the amp is not getting enough power when it hits, it could be causing a buzz sound.  Does it act differently from when the car is off or when the car is running?  Whatever the circumstance, it sounds like the amp circuitry causing the buzzing, and the best fix, after insuring there is plenty of power, is getting a better amp.  Hope this helps, Scott