The amp has a lot of power and will effortlessly drive the HD6XX in both balanced and single-ended to deafening levels, also the specs are virtually similar for both so there will be no audible difference. So the cable won't change anything with this particular setup. If you absolutely want another cable for some other reason (maybe you want a longer/shorter length or something that looks more aesthetic), I'd suggest something like the Tripowin GranVia or Hart Audio balanced (4-pin XLR) cable, and then you can use a 4XLR to whatever adapter if you ever need to use your headphone on another device that does not have XLR balanced and only 4.4mm balanced or SE. If you're strictly looking to find a sound quality improvement, then save your money, the cable won't change anything in that regard.