I would NOT recommend a Shiva: it is a very nice cord, but lacks "flesh on the bones." At the very least, one needs a Vishnu, but even this is not enough, I think. Having had all the Nordost cords, I opted for Shunyata power cords for the lower noise flower (Valhalla WILL have a lower noise floor than a Python Alpha: not so sure about the Phython Alpha Helix). The Shunyatas have considerably more tonal color, are dynamic and music sounds like itself, instead of a skeleton of such.
I'm sure there are other contenders, but be careful NOT to use the power cord to compensate for flaws in your system. You will never have a truly balanced system if you go that route.
I'm sure there are other contenders, but be careful NOT to use the power cord to compensate for flaws in your system. You will never have a truly balanced system if you go that route.