I'm in a hard rock/metal band and play with my fingers. I've always had this 'clank' to my tone the heavier I play/hit the strings with my plucking hand that becomes very apparent the harder I play. This leads to a sharp, high pitched sound that I really don't like. I'm fairly sure it's from my hitting the strings too much in an 'up and down' fashion (like slapping), as opposed to 'side to side' if one were playing with a pick. Outside of changing my technique much, anyone have any suggestions? This doesn't happen to me when I'm playing our less aggro music like Zeppelin.