Jeff Rowland with Rel sub

I recently purchased a Jeff Rowland Concerto integated amp. While the amp is incredible, I cannot figure out how to hook up my Rel Strata sub. Something is different about the Rowland that makes it more tricky or maybe impossible, so any help would be appreciated. When I contacted Rowland they suggested getting in touch with Sumiko. When I contacted Sumiko they said to get in touch with Rowland. Anyone have the same problem? Solutions? Thanks, Jerry