I have done this operation a number of times.
The Rega arm is set up with RCA cables coming right out of its base. But if you take it apart, what you find is that there is a tiny dime-sized round circuit board on the other side of that rubber plug that is in the base of the arm.
This allows you to set up balanced operation. Follow the regular color codes: black shield for *both* channels and pin 1 on the XLRs, red pin 2 of the right channel XLR, green pin 3 of the right channel XLR and so on.
The problem you will run into is that there is not a lot of room. Usually what I have had to do is use a drill to go through the rubber plug to make more room for the cable I am using.
BTW, for that I usually use Mogami Neglex console cable. It is only 1/8" in diameter, is OFC and has a twisted pair inside with a shield. What you will find when you go to balanced is that the interconnect cable plays a minuscule role in the overall sound compared to single-ended so using a cable like this is absolutely no worries for the audiophile nervosa challenged.
Good luck- don't rush it :)
