I might propose something from a different angle:
A modifier key which allows “safe” mouse ball use while hovered anywhere over the mixer window. ie. no controls will respond to the scroll wheel/ball while the key is pressed. This way, you can enter values with the scroll ball AND have safe window scrolling too. 
* I can’t stand trying to turn knobs with a cursor, so I frequently use the mouse ball to enter values. BUT, I also use the mouse ball almost exclusively to navigate around my windows.