I think OP has a big question mark in his brain and that let him to ask again. Very similar with me.
On this forum, people said it again and again ,it is the better choice to use XLR input, but why there is so many RCA pre or amplifier on the market, especially for some main Street brand like CJ.
In my personal experience, RCA connection bring very good experience, even better than XLR.
All in all, it goes down to the design of the amplifier, the connection won't decide the sound in large percentage.