Since these devices output near perfect power, what is the benefit of connecting your components to the P5 or P10 with expensive power cords?
Better power cable = less degradation (not more improvement). In other words, when starting with perfect, end up with perfect. Rather than, starting with less than perfect, end up with perfect.
Also better shielding, and less restriction to be specific. But Brodric is right.
Do you have a recommendation on which PS Audio series cord AC-5 vs AC-12 would be best for the P3 power plant?