How much difference between balanced XLR and RCA

Check with your manufacturer, some that I know of say that their component is designed to run either balanced or singled ended better than the other, but offer both ways for connection. Musical Fidelity for one beileves that their components sound best with singled ended, and thus, don't offer balanced outputs, or inputs.

Also depends if your living environment has alot of RF noise. Balanced filters all of that out. If you live out in the country, it doesn't matter. If you live in the heart of Manhattan, you may see some benefit.

I have heared many times that RCA out of a CD Player sounds much better than XLR. I think you should try yours out and see if it does or not.
Note: I use all XLR

Most important is the signal fed into any cable, balanced or RCA. Even the 'best' balanced cable can't improve a bad signal. The Meridian is a very nice piece of equipment, so if that sounds better to your ears, forget about the type of connections and enjoy the music.

Eandylee, a differential amp is one where each of the signals is run through it's own amplification stage: Right hot, right neutral, left hot, left neutral. This requires a very careful matching of output devices (e.g., FET's). That's my understanding but I'm not an engineer so I may have misinterpreted something along the way. In any event, they are best served by XLR cables. My phono preamp will not accept an RCA and I had to go through some very interesting cabling mods to get everything to work right.