Do you have a schematic were you put this?
Before the key input or after your overdrive pedal and then the lehle and then in your input of your amp?
This is my setup where I use the zuul/sun in the fx of the preamp and a signal in the key of the zuul/sun and also from my overdrive to the input of my preamp (Kartakou colossus which goes from a y cable into the dual input of the Mesa 2:90)
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