this article by Jon Risch may help.
Some cable companies will custom make a cable to spec for you with XLR on one end and RCA on the other. I used Stealth cables for me ARC LS2B to used the balanced section. I sold the ARC so also am selling the cables. One has already sold and shipped but the other is still for sale here. I'd definitely recommend the Stealth cables as an excellent choice, but they are Silver and very revealing. I loved them in my application. Other cable companies will do the same terminations on custom order.