The XP-30 is a true balanced design, and why the RCA has to use a shorting PIN jumper used with RCA (to remove the negative voltage channel). You can do this two ways…
-) if you use a XLR to the amp and the SE amp has a cheater arrangement (steals PIN 2 to PIN 1) this negates the XLR’s function to a single ended arrangement. Here it is better to use an RCA as that’s how the signal is being “moved” down the wire.
-)Some units are balanced out only, and if you go very far it is better it is better to use a differential amp stage at the amp, and convert the signal to SE at that point so the signal is “moved” from A to B properly and with minimal noise.
-) If the SE amp has a true differential input circuit inside, that converts the balanced input to a single ended input use an XLR from the true balanced preamp. This will keep noise out up to the difference amplifier in the amps front end. It is rare that single ended amps have the proper balanced input option that is then taken SE from there into the amp past the input stage.
-) if you have a single end only preamp to a balanced only input amp, convert the single end at the send end to XLR with a differential amp. Thus, send the signal the longer distance over XLR.
If you are using a true singe ended amp, yes, use a true RCA cable to get the best possible noise performance going to your amp from the XP-30. If the amp is balanced internally, you’d want to use the balanced out.
If you use a XLR to a single ended amp with a cheater input circuit, the XLR cable will not work as well as a true RCA and is exactly WHY I won’t wire an XLR as and RCA. Use the right cable so it works at it’s peak design potential.
Most better / worse than issues are simply a mismatch in the proper cable’s between each component. I use BOTH RCA and XLR as appropriate and there are indeed appropriate uses.
Best,
Galen Gareis