Emailed Nik at Ceriatone asking for advice and he told me to start with the Master and Volume at 1 and to set the OD to more of a cleanish setting, because higher gain acts as kind of a boost in itself and so when pushed the OD channel will be less effected by the Preamp Boost. It sure did the trick! I can get both channels and their boost balanced now. Another trick I found is to increase the Treble middle and Bass controls and lower master to lessen the amount of boost since it works by lifting those controls from the circuit. He also recommended changing the 22M Resistor to a 10M to lower the boost volume.  Amp sounds great and Nik was extremely helpful!

I have almost the exact same issue. The clean channel doesn't get as loud as it should and is much more affected by the boost than the OD. Were you able to find a solution?
Edit: Lowering the gain to cleanish settings balances the Preamp boost. You can also decrease the overall amount of boost by increasing you Bass Treble and Middle controls and decreasing Master to compensate.

Looks great! That's a sweet cab! How you liking her so far?

I couldn't figure this out either so I wired it up as shown on the old layout. Works fine aside from a possible issue with the boost but I doubt they're related. Good luck either way!

Hey all! Just built a new OTS Mini and was wondering if it's normal for the clean channel preamp boost to be much louder than the overdrive channel. The OD PAB seems to be pretty reasonable volume wise but when used on the clean channel it more than doubles the volume. It seems a bit too extreme to be useful so I'm wondering if I screwed something up here. I reflowed the solder on most of the preamp and any suspicious looking areas elsewhere but no change. Thanks!