in some metallica songs (fade to black, call of ktulu, sanitarium, ect.) they use a really very beutiful clean sound. does anyone have any idea how to duplicate this? is it the amp? the kind of wood in the guitar? the emg pickups? an effect? I know it's on an electric because I have videos of these songs live. if anyone knows how this may be done or how I can come close, please tell me.