I don't see how the choice of cables will have much effect in ameliorating noise due to the tubes. The presence or absence of shielding on a cable will help to block (or not block if no shield) RF, but that is an external problem, and noise due to RF is of a different character compared to tube noise. Just spend your money on low noise selected tubes from a reputable source, e.g., Upscale Audio, to name one I know of. Ralph likes to remind us that sometimes very expensive NOS tubes are not "low noise". You may be better off with Russian or Chinese tubes of recent vintage, if noise is paramount.