You might want to search the topics on Balanced tech. And, PM fellow Audiogoner Ralph Karsten (atmasphere).
Though a piece of equipment might have balanced input/outputs, if it doesn't support the AES standard, then all bets are off. True balanced design will remove the grounding issues and allow the cables to work while minimizing inherent 'cable sound'.
Also, you need a system that can allow you to hear the difference between XLR and RCA. A basic system might not let you enjoy the benefits that you would enjoy with a higher resolving system. My 2 cents...
Bob