You could try the Amperex JAN (Joint Army Navy) 7308, white label. For my taste, they are my favorites. Note: Only two (2) are required.
Tube upgrades for SF Line Preamp
I recently purchased Sonic Frontier line preamp and upgraded the standard 6922 tubes to valvo tubes. Like most audiophile, I am needlessly spending more money hoping to achieve that 1% increase in sound reproduction. Does anyone know what other tubes I can upgrade to in order to get me to that next level?