I use a Purist Audio Dominus power cord on my Rowland Model 1 and love it. It cost me more than the Model 1 (I bought it used...the Dominus was new). It didn't sound anything like what I expected. I expected more bass and bigger dynamics. But instead it smoothed out the midrange and top end to the point where I had to buy it. Once I heard it I couldn't go back.
Jeff Rowland likes Cardas for all interconnects, speaker cables and power cords. I haven't tried Cardas but Jeff ought to know.
Cables and power cords will never fail to amaze and baffle.
My only advice is to find a brand you like and go straight to the top...get the best one they make and you'll never look back. Good luck.