I don't necessarily agree that silver cables are always the way to go with tubes. The other factor is the speakers themselves. I have tried the Harmonic Tech Pro Silway silver cables with my all tube system AND the Merlin VSM-SE speakers. The Harmonic Tech Truthlinks proved less bright and a better overall match. So the answer isn't always silver with tubes but lies more in the balance you are looking for and what is going to bring out that balance based on the rest of your system.
CABLES for Tubes?
what are the best interconnects for a tube amp and Tube tuner and to a regular CD player and SilverLine Speakers