Modified with transformer, Automatic EQ compressor. This design allows deep bass and impulse response to be enhanced and less high frequency attenuation and clarity enhancement circuit. Unit has a ground modification and capacitor update for 6db noise floor improvement. This version has a 4560 op amp upgrade for line out balanced out. Mic pre amp RFI suppression capacitor. Modified with first stage tube harmonic bias control (right control) Cleaned switch with silver paste. #9 condition