Different RCA cables can make a difference but only if you were really using crappy connections to begin with or there was a problem with the setup, either way the perception of two different but still high quality cables would be too small to blind test imo (assuming very short lengths ). We would be getting into the arguments of High quality standard copper cables vs strand insulated, time aligned, reactance controlled, magnetic flux tubed cables, which would be hard pressed to tell the difference at least on low or even mid fi equipment.
One thing that would be worth doing is using that XLR connection, that's something all can agree on makes a difference.