also, i've been learning about extraneous sounds that you don't want from too overt movements. ie key slap, buzzing bass notes. if you don't have any space between fingertip and key - there is no extraneous sound from tapping the notes. you'll hear this with some fast bach pieces (slap slap slap). also, if you press bass notes - just to the point that you hear a good tone - it sounds much better than bZZZZZZZZZ vibrating around the tone.