According to Bob, at The Cable Co, the Synergistic AC/Master Coupler is a great match with McCormack amps.
Power cord and interconnect advice
I recently purchased a MacCormark DNA 125 and am looking for a good match in a power cord. The remainder of my system is made up of: Denon AV4800, Toshiba 4205 DVD, Mirage OM 8's, Mirage center and surrounds, and a Mirage Frx 12 Sub. I would also welcome advice on interconnects, I am currently using Nordost Solar Wind speaker cables and interconnect between the MacCormack and the Denon.