power cords and krell amps any suggestions?

I'm thinking about upgrading form the stock cord for both of my amps a Ksa 200s and a Kav-500 3. We are using the Audioprism
Power Foundation lll, I also have 2 20 amp dedicated circuts for the system with the orange heavy duty recepticals. Which power cords have you tried and what were the results? Or would I be better served upgrading my recepticals first? I would like to here from Krell owners but of course all imput would be helpful.
Thanks for your help.