Hate that. Had something similar with my Zu interconnects. It took me forever to solve and they helped but now I don't remember how it even got fixed. I think I bypassed the ground to my amp instead of pre-amp.
@HiFi Guy, ya, I had the same issue with the Pangea's way back when, switched everything over to Blue Jean, now I just replaced a 6' with a 3' and it buzzes, go figure, lol