ARC REF 3 20 amp to 15 amp power cord adapter

I recenlty purchased a REF 3 preamp. I would like to experiment with powercords and then purchase the one that works the best. I have several different powercords at home I'd like to try.
Where can I purchase an adapter that will allow me to try my regular 15 amp powercords and plug them directly into the REF 3?
The REF 3 only uses the 20 amp I'm told because it makes a better connection, as the rest of the pc is 15amp from the wall.
Thanks for your help in advance.
Here are a couple:
Vodoo makes a nice adapter
I second the Vodoo, I own one and like it very much.
The price is right too.
Shunyata also makes a very good one.