suggestions--power cords

Running Conrad Johnson ET 250 S and ET 5 with Vandersteen Quatros--currently, Mccormick DP 2 for CDs---finding issues with getting sound I like---running my Kimber Palladian to the Pre--which seems to work great--but as for the 250 S----have tried numerous combinations---Shunyata Python, Cardas Golden Reference, ---focus is good, but sound and stage is muted. Ideas? Also, could use a good reference for power cord for Mccormack---another Kimber for the 250S? Any and all input from people with similar equipment very much appreciated.