Hi 3chihuahuas, I agree with Zenaudio call Kevin Upscaleaudio.com he will fix you up. He knows your pre-amp and he knows his tubes.
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?