I think what you're looking at is a C7 socket/connector. (The 3-prong is called an IEC.) A few cable companies make cords terminated with a C7--PS Audio is one example (though I'm not necessarily endorsing that product). Visit a site like Audio Advisor and see if the photos match what's on the back of your units.
Power Cord Question
My system is more on the budget end but some of the components have detachable power cords with two prong connectors/terminals on the rear. I notice that most upgraded power cords have connectors that plug into equipment having three prongs. Can these 3-prong power cords be used to plug into the rear of components having only 2-prong connectors in the rear without hurting anything or degrading the sound? Thanks for your input.