For sale is my immaculate, barely used J-Retro preamp with original box and paperwork. No scratches on the control plate. Only installed in a bass which I'm now selling, so moving on.
This is the "Flat Response" version. Basically, this takes away the slight scoop at the flat setting which is built into normal J-Retros, thereby giving you effectively the passive tone as the starting point. However, that scoop can be dialed in and the rest of the tone and boost settings are still present and correct, giving you the J-Retro sound.