is there a way to add a VTC to an existing 4 POT on board pre WITHOUT replacing the existing separate bass & Treble controls with a stacked pot? I want to install this NOS MetroExpress pre in another bass with umpteen holes (7). I’d rather just add a standalone tone knob that would work when the bass is in active mode, than deal with a stacked tone that switches active/passive circuits, when the existing circuit already has that feature. I recently made an error purchasing a ToneMonster 2 band pre with a tone control, only to find the tone control only works in passive mode. The sound isn’t providing what I was hoping for either, and I’m going to return it. I have a perfectly usable pre right here that I already know I’ll like the sound of. I just want to add a VTC without any other mods. Anybody got a wiring diagram? With POT and capacitor values?