velodyne DD hook up

OK for those of you with Velo DD drive subs, what method of hook up are you using? RCA or XLR from the pre-outs to the sub in, either single runs from a "y" or dual RCAs, or speaker wire "paralleled" with you main speker runs? Any sonic pro/cons to one set up vs. the other. This is for a 2 ch. application integrating with monitors.
Thank you.