I would agree with Ralph and would like to build on his point. One of the major benefits of XLRs is "common mode noise rejection." In a fully balanced system, you get this when using balanced interconnects. The signal is sent twice. The second transmission is the inverse of the primary signal. If there are any commonalities between these two signals, it is rejected as noise. This requires every part of the circuit to be doubled though and drives up the cost of equipment.
If you have a system that is not fully balanced and they have simply added XLRs (very common) which require a transformer to convert the signal from single ended to XLR. If thisr is the case, there is a good chance the XLRs will not be the best sounding interconnects and you may gain some noise benefits between components over long runs (20+ Feet), but it will not deliver the kind of benefits you would get from fully balanced gear.
Over short runs, if the gear that is connected is not fully balanced, there is rarely a benefit in using XLRs over Single Ended cables. And in many cases, if the transformers used to convert the signal from SE to Balanced are cheap, it will sound worse.