SQ difference XLR vs RCA ?

@gillsysb 

Thank you for your comments. Let me respectfully ask one question… is there a chance that you were reacting to the increase in volume and not the quality of the sound? It is really easy to react to the increase in volume… which does not in any way enable your system an advantage. 
 

I am fortunate enough to have a preamp that allows me to easily equalize volumes and then make comparisons. 

All my equipment is balanced (Audio Research Reference) and Audio Research recommends using balanced. I have tried both. I was unable to hear a substantial difference. Since, more and more manufacturers are headed that way (I think), I went ahead and switched over all my interconnects. More as a just in case thing.

If my system was not in what I consider it’s apex state, I would not have changed over. I would have applied the money to improving components. There may be other components more sensitive to the interconnect used. I am sure Audio Research put a lot of effort into converting the signal from balanced to unbalanced… this is audiophile stuff. They want every input and output to sound good, but extra conversion is never a good thing and tiny differences add up to making an impact. So, it depends on where you are in system building if you should worry too much about this.

No. The difference is incredibly subtle and contingent on your specific components and length of run (if dozens of feet). When you get to own the best system you have ever imagined… then bring this issue up again. For now, rca will do the job and cost less.