Best Power Cord for Phono Stage

Phono stages usually do not demand much current (tubes need more than transistors however), and you probably want a shielded cable to keep out RFI, as far as is possible. So with those two criteria in mind, you should be able to narrow down the possibilities, or widen them, as the case may be.

Check out JPS Labs Analog power cord

A standalone phono preamp (tube or ss) should have a separate PS to be worth its salt (with a VERY FEW expensive exceptions;--) -- and those (separate power supplies) will have RFI filtering built in.

A phono'stage' customarily refers to a built-in phono preamp section in a normal preamp or a receiver. And you have to decide how much differenc a special power cord would make in that situation.

Even with a well designed phonostage with an outboard power supply, the power cord which you use can have a rather dramatic impact on the sound. Two cords which sound very different but each of which is superb are the Bybee Millenium and the Jorma Prime. Both incorporate Bybee modules which seem to work well in this application.