Congratulations on a great speaker purchase. Consider the Townshend Platforms which are my personal preference. They are tuned for the mass of your speaker.
Your power supply drives your field coil and may not benefit much from an upgraded power cord, depending on how much reserve energy is stored in the power supply. It only puts out a few watts per speaker. But I never take any chances. I focus on the gauge of the power cable more than the claims of the maker. I'd go with a 12 awg cord.
Jerry