So my current setup i have is numark mixtrack pro connected to my laptop and A pair of APS15 to the back of the mixtrack pro using both out put 1 and output 2. I know no that the ouput 2 on the mixtrack pro is for cueing/ monitering . so here goes my question. How do i connect the 2nd APS15 without using the output 2 ? I have heard aout a RCA splitter but i dont really know what that is . Sorry if its a stupid question