I remember fiddling with off brands and some inexpensive Shunyata power cords to no effect. This was ten or fifteen years ago.
With my newer Audio Research amps they come with heavy duty copper and 20 amp connectors, so I couldn’t use any of my stash. So I rotated through every Cardas line, all of which were pretty much instantly obviously better… but also tipped the tonal balance slightly and the AudioQuest Hurricane which just improved every aspect of the sound and was completely neutral.
OP.
What I would recommend is to find a way to borrow an Audioquest Hurricane. These things took the audio world by storm a couple years ago. The difference should be instantly obvious and overwhelmingly positive. If not… fantastic… the power cord has no effect on your amp… you are lucky. You know for certain. End of story.
Otherwise you have a data point. If it is worth it… well, I know of incidences when an absurdly expensive cord is performance justified. Or drop down a level in the storm series.
Also, the Audioquest are incredibly tight fitting… on purpose.