You say you have a 4 axis lead shine 4660 but you only have X,Y & Z Hooked up to it. That is three axises so what is the fourth being used for? Also this question probably depends a bit on what you are using for control software. Also I'm not grasping what you are talking about as far as breakout boards as the Leadshine has that built in. In any event where you connect a board depends upon where your software is sending the communications for the axises attached to that drive.