Should power cords for power amps be shielded?

I do not believe there exists a set rule about shielding of power cords on any amps, one way or another. Personally, I have experienced the most desirable results on my SS class D Bel Canto Ref 1000M monoblocks and Rowland 312 stereo amp with the completely non-shielded Shunyata King Cobra CX power cords, which IMO yield optimum nimbleness, resolution, extension, and authority, without emphasizing any particular region of the audible spectrum. On the other hand, other audiophiles may prefer cords with slightly different audible characteristics. . . some may be shielded. . . and some may be unshielded. G.

The King Cobra is a ne plus ultra cable with 600 individual oonductors, I would expect it to sound fabulous compared to most other cords, shielded or unshielded. I believe Shunyata employs a mind-bogglingly elaborate conductor braiding to achieve the effect of standard shielding. There are exceptions to frustrate every "rule." I'm looking for guidelines -- generalizations about "most systems, most of the time."