My speakers are 4 ohm nominal. I had been using 7 ga. 8 ft Acoustic Zen Satri Biwire cables with my ncores, but recently went to 10 ga. 8 ft. with absolutely no negative results. It still sounds fabulous, with the remarkable bass control that is a hallmark of these amps. My system is very high-rez. In spite of Jim Romeyn's findings, I haven't found the impedance sensitivity he talks about.
If you use low impedance loads, it is still a good idea to use pretty large ga. and short cables, but I don't think you need to go overboard either.