Robb, whether you use a balanced cable with XLR plugs and then attach an RCA adaptor on the end or use a ready-made XLR-RCA cable should make no difference if both cables are similarly shielded. In either case the connection is unbalanced, since both the output device and the input device have to be balanced for a possible interference reduction advantage(not usually needed with a typical home level of interference)to exist. The balanced output sends out two signals(rather than the one on the central conductor of a coaxial cable)on the two conductors of the balanced cable with XLR plugs, but one of the signals is electrically inverted 180 degrees by the output device. Any electrical interference impinging on the cable is almost equal in strength on the two conductors and is in-phase on the two conductors. In the balanced input device the signal on one conductor is again inverted by 180 degrees so that the audio signals are in phase and instead of cancelling each other result in a 6dB higher signal(a doubling of voltage is 6dB). Any interference on the conductors, on the other hand, is cancelled by the inversion. Again, for most uses the interference rejection of the typical shielded coaxial cable used in an unbalanced connection is sufficient.
