Rogue Tempest II tube rolling

Just curious who's swapped some tubes in the Tempest II & what changes occured. I just got mine yesterday and will start by swapping the Sovtek 12ax7's for some NOS RCA 12AX7a's. Right now im interested in changing the 6sn7 driver tubes from the Shugyang stock tubes that came with it, im thinking maybe some Sylvania's? My setup is:
Musical Fidelity A3.2 CD
Tempest II
B&W N804
I have had nice results with Telefunken 12AX7 and Sylvania 6sn7. It has been awhile since I switched but recall a subtle refinement rather than something more than that. The Tempest II has been great and a good upgrade from the original.
Thanks for the input! I rolled some Mullard 12ax7 box plates & noticed a wonderful change in teh sound, bass is much deeper & soundstage is wider than with the Sovtek LPS stock tubes
Use a 12BZ7 in place of the 12AX7 on the Tempest MkI. The sound is fantastic and Rouge told me the Heater Supply would easily support the added current the 12BZ7 requires. This substitution is often done on Cary gear and is where I got the idea. Makes the Tempest much more authoritative and dynamic.