I would say, use the VPI cable on the tonearm at first, that is VPI's recommended cable. But try it both ways of course. Are you saying there are only 2pr interconnects supplied terminated with RCA's? Alex makes a specific cable for the tonearm if I'm not mistaken. Try adding one cable at a time and listening it's all cumulative. I did it, Interconnects, Speaker cables, Power cables because I had the Power Cables last.
Nice setup, you should hear differences, please do tell us your impressions.
D