My speakers are crackling.?

SOMETIMES THE SPEAKERS WILL MAKE A CRACKING SOUND BECAUSE THE UNIT 1- DOESNT HAVE ENOUGH POWER TO BUMP ALL FOUR SPEAKERS AT THE SAME TIME MAKING THE QAULITY SOUND DISTORTED AND LOW 2- ONE OF THE OUTPUTS OF THE UNIT IS DAMAGED,SOMETIMES THIS WILL HAPPEN IF THE POSITIVE AND NEGATIVE TOUCH. HOPE THIS HELPS U