I almost think of drawbars like EQ in the sense that the left ones in a set give you more bass while the more to the right is the treble. So if you pull out only high ones you'll get a bright sound without much body with is great for screamin' solos but not too good for rich chords but if you pull out the lower ones you'll get a dark sound but it'll probably end up muddy in most registers...as far as drawbar registrations, that's all up to you, just fool around and see what you like