I have experimented with power cords for the Levinson 334 and have found the Shunyata Python, Custom Power Cord Co Top Gun HCfi and the Synergistic Designer Reference Squared to work very well in my system.
In short, I found the Python to add a nice touch of warmth and smoothness to the 334 which is certainly not a bad thing. The Top Gun HCfi was the most neutral of these cords as it did not seem to add or subtract from the sound, very effortless with a quiet background. The Designer Reference Squared is similar in quality to the Top Gun HCfi except perhaps more dynamic with a larger soundstage.
In short, I found the Python to add a nice touch of warmth and smoothness to the 334 which is certainly not a bad thing. The Top Gun HCfi was the most neutral of these cords as it did not seem to add or subtract from the sound, very effortless with a quiet background. The Designer Reference Squared is similar in quality to the Top Gun HCfi except perhaps more dynamic with a larger soundstage.