Mix RCA With Balanced ??

Well hard to say.
My system is also part RCA, part XLR.
I run a XLR from pre to amp due tothe length of 7 meters needed.
I would try a RCA there but I do not want to pay $$$ for a 7 meter RCA pair just to see if it makes any difference!
But for shorter runs Hell Yes try ech type aand see if it sould better.

I have a few items connected to both outputs for various reasons.. yes they can sound different.

Is one automatically better? no. Does it matter if I have some RCa and some XLR who knows.. It is what i own, I am not going to buy stuff to fulfill some persons fantasy theory.
Basically don't worry about it.

Balanced cables are useful if you are having noise and hum problems.Other than that,it shouldn't make any difference.

Get rid of the CJ and get a fully balanced preamp and use balanced cable throughout. I've never heard the CJ, it has a great reputation, but so do other tube based balanced preamps (Atmasphere, ARC, BAT, EAR, etc.).