Just in we have a USA made RT-902 tube preamp in excellent condition. This is the rackmount version of the 'Concept & Design : R.K Butler' Real Tube Overdrive. This unit has a green 'Keynote Industries Copyright 1989 BK Butler' circuit board. There is no evidence of any service work being performed inside. Hand engraved serial number. Pots are cleaned and quiet. Everything functions as it should. The rubber feet are still on it. No 'rack rash'. Preamp tube is 12X7A Real Tube branded. 

Front Panel Controls: Boost (Rocker Switch), Bypass (Rocker Switch) Drive, Contour, BIAS, Master and 3-band (HI, MID, LO) EQ
Rear Panel Phone Jacks: Foot Switch Bypass, Foot Switch Boost, Instrument In, Line in, Instrument Out, and Line Out 

Please note that when you adjust the bias you will hear something similar to what a dirty pot sounds like. That only occurs when when the tube bias is being changed and is a function of the design.