Maybe we should ask @atmasphere ? And avoid descending into extension cords, which have nothing to do the power cords on these amps...
Power cords affect audio equipment due to voltage drops occurring at 60Hz but also at much higher frequencies.
The more feedback you have in an amplifier the greater its ability to reject anything that isn't the signal, such as noise,
As a result, the class D is relatively unaffected by power cords at low power levels. But as the power is increased the power cord would be more important. It will not affect the amp nearly so much as power cords affect our tube amps!