In my arc system, balanced xlr cables wins hands down over single-ended rca's. I'm embarrassed to say the balanced cables are my own cheap diy canare star quad vs expensive top of the line furutech rca's. As some have said before, use the connection (balanced or single ended) that your system was designed and built for. After that, experiment with different conductors, and connectors of the cables. If your system is good enough (and your ears) you should be able to hear the differences. Just my humble opinion, of course...
