+1 great post. I agree.
Also, I think you can find much better cords than you are using. I only tried one of the Pangea but it was not very effective, so I never tried more.
Certainly one can try experimenting with material for isolation. But reputable companies have done this for you with every aspect of the cord. The current Storm line do AudioQuest is an example of this. The fittings are so tight I have to hold my mono blocks when plugging in. The improvement in sound from my amps was simply stunning.
I also recommend changing one cord at a time. Experiment with the amp cords first. While every component gets an improvement, the amp is likely the biggest difference and most obvious in the change you can expect for a power cord.
Even if you think you would never spend as much as an Audio Quest Hurricane, I recommend you try one. It will set the bar for what a high quality power cord can do. Definitely plug the amps directly into the direct lines.