I use the Purist 20th Anniversary Contego Power Cord. I have compared it against the Stealth Dream, the Shunyata Anaconda Alpha Helix and the stock AR cord. My amps are the Lamm Ref 1.2 monoblocks. In my system, the Purist is a slight flavor improvement against the Stealth and Shunyata, and a significant across-the-board improvement against the stock cord. If you are using a Ref 3, you owe it to yourself to audition as many PC's as possible. These PC's are not cheap, but do make a difference. Just my opinion.