The first issue I think would be a problem is putting the Wah in the FX loop. I take it this is a typical guitar Wah. Wah’s are rather sensitive to what signal impedance is put into them. They’re looking for HiZ inputs. Have you tried the FX loop without the wah? What synth pedal are you using? Does the synth pedal have any wah type FX? Something like the Boss Synth pedals should handle a line level signal well. I’m not sure the Mixinglink is going to help you with the wah. I hope I understand your setup correctly.
