If you mean biasing the tubes, the tubes in pre-amps do not need to be biased. Sonic Frontiers will sell you matched pairs for your pre-amp, but matching is different than biasing. I have re-tubed my SF Line 2 with matched pairs of tubes several times. Good Luck. Craig
Does anyone ever retube Sonic Frontier preamp. SFL2?
Do you know how to rebalance the new tubes or has instruction how to do it? Thanks