Tube Recommendation for Anthem Integrated 2

Any recommendations for upgrading the pre-amp tubes for an Anthem Int 2? Currently using Sovtek's. I listen almost exclusively to classical and jazz, and am looking for a smoother sound and tighter bass, while retaining high end clarity and mid level detail. The Int 2 uses two ECC88/6922/6DJ8's. Thanks!
Amperex 7308 is one of the better choices.
also Sovtek 6922 sound better than most 6DJ8
You might try and find Brimar 6922. Anthem uses these in their upgrades. I installed one in my Anthem CD-1 CD player.
Should give you a warmer sound. Good for jazz.
I used to have the Anthem Pre2L preamp. I tried Siemans 7308's per Kevin Deal's recommendation. I then tried Amperex 7308's due to alot of recomendations here and over at the audioasylum. I prefered the Siemans over the Amperex for the Pre2L. The Siemans gave me exactly what you're looking for -- smoother sound and tighter bass. The Amperex also sounded good but the vocals were more forward, a little more energy in the highs, and the bass was a little more rounded and relaxed. I'm sure others may prefer the Amperex, depending on their system, room acoustics and personal tastes. The Siemans are noted for tight bass. I now use the Sonic Frontiers Line 2 with 6 Siemans 7308's.