Correct me if I am wrong but I believe that class D amps do not have power supply caps used for storage ... so it may behoove users of this class of amp to go to a larger gauge power cord to act as a temporary reservoir on high current demand passages
The larger cable wouldn't be an actual reservoir as in storage but a bigger cable would allow for more instantaneous deliver on strong peaks
With the high efficiency of the class D amps you will probably get a 16 or 14 gauge power cable from the factory ... increase it to 9 gauge and reduce the restriction if and when a peak in the music calls for more instant current
I wonder if those who have had success with after market power cords on class D amps did so from the after market power cord being a larger gauge ??