Tube recommendations for my Rogue Audio Cronus ...

Contact Andy at Vintage Tube Services. He can offer some great recommendations for your equipment. I use him exclusively with great results.

In my VTL ST-80 I have never found better sounding tubes than the Genelex Gold Lion KT-77's. Unless you need more power I would get another set of the Gold Lion's. Also what makes you think you need new ones. Find a tube tester and check them out. Unless you are just looking to change the sound.
Alan

I agree that the GL KT-77 sounds great. If you liked the Svetlana EL-34 you might also want to try the Tesla E34L tube.

I have been extremely happy with my GL KT-77's. I'm just thinking ahead, as we all know (or am I wrong ?) that power tubes should be replaced every four years or so. Should I be proactive and replace them in a few months, or should I wait for a tube to fail ?

It never hurts to be proactive. If you have 3 to 4 years on your tubes , I would say replace them.