BAT VK-3i owners.....tube types for rolling?

I've searched the sight and did not find what I was looking for.

Recently aquired VK-3i and VK-200 and am very happy with the musicality of the pair but the pre is getting up there in hours and don't know the age of the tubes. I am looking for your input on tubes you've used and the sound they gave.

Currently listening to either Thiel CS 3.6 or Paragon Regents and music is mainly jazz, big band, classical and lots of horn sectioned bands.

Thanks for any input you folks have and HAPPY NEW YEAR TO ALL !!!