I have had good success using power cords from PS Audio. They are well built and have some engineering behind them. Paul McGowan at PS Audio indicated to me that the most important power cord is the one going to your power center.
Option 1 (no power center) - get a duet power center and a PS Audio AC-10 power cord and run it to the Duet.
Option 2 (have a power center) - get a PS Audio AC-12 and consider running it to the power center.
Option 3 - if you have a good power center and a "killer cord" supplying it, get a PS Audio AC-10 for your source.
Option 1 (no power center) - get a duet power center and a PS Audio AC-10 power cord and run it to the Duet.
Option 2 (have a power center) - get a PS Audio AC-12 and consider running it to the power center.
Option 3 - if you have a good power center and a "killer cord" supplying it, get a PS Audio AC-10 for your source.