I agree with @thecarpathian - the Amperex (made in Holland) is a great choice: neutral and smooth at the same time. My preamp takes five of them.
Tube rolling with Rogue Audi RP-1 Preamplifier
I own the Rogue Audio RP-1 preamplifier and currently use stock tubes. I was reading that I can improve the sound of the preamplifier by replacing the stock tubes. Can anybody advise specifically what tubes might be an improvement over my current current tubes. Thank you.[