Besides the 6db of gain, you MIGHT have a quieter signal from your preamp to amps withe XLR. Years ago I had a system that was crazy sensitive. Some of the issues were from the built in phono preamp, and XLR IC’s did help. Since then, I’ve haven’t gone longer than 3 meters between my preamp and amps and in my current home, with my current system, RCA’s have worked just fine.
All the best.