I have a leonardo and what I love to do is have a circuit that when you're holding the button down it drops the sound level down from (Let's say) 50% to 25% and then once you let go off the button it restores it back to 50%. Is there any real way of doing that? Thanks in advance! 
Drops the sound level of what?
If you can figure out the keystrokes to do that, you can make the Leonardo send those keystrokes.