The XLR will give you 6db of additional gain and is theoretically more quiet..
I confirm .. not theoretically!
I used RCA cables between my Whest Audio 30RDT and the Pass X1 preamp and lately the same cable but Balanced and now I have more audible gain (4db not 6)and more quiet or better less audible blow from the tweeter even if the 30RDT is silent like a fish also by RCA