Would using RCA to XLR conectors screw up sound?

Just was perusing ads and saw an amp I was thinking of giving a twirl.Seller says it was made special with XLR inputs ONLY and os "fully balanced" (I'd have to check with manufacturer as I have two components now with bot connections and circut topology is notbalanced).I read in Hartley's high end book that going form balanced and unblanced back in forth in chain can do more harm than good and one might want to keep it single ended all the way through to avoid this.I wondering if anyboy has a take on this.It sure would be at least to use a long ass cable to go form the rack to the power amp between speakers.Opinions?
Chazz