Being balanced doesn’t change anything. Your cable might not be optimal length, but these calculations depend on many factors, like output transition time of the source, signal propagation speed in the cable etc. Also, this cable might be a perfect characteristic impedance match in your system (no reflections at all). The best way is to borrow one and try. Your ears will be the best judge. Mismatched cable induces time jitter of digital signal, that translates as noise added to music (not present without signal/music). This noise will make sound harsher, brighter with possibly worse imaging.