One way to do it, woiuld be to get an EB Volume pedal
, the 6166. *It has a seperate out for the tuner. *Splitting your signal after the preamp is going to cut the signal in half either direction. *The volume pedal has the circuitry to keep the signal strenth the same.
That's what I would do.
Anyone else got a better idea?
oh, if your processor has a stereo out, and you can control each channel, you could do the right channel as YOUR processing mix, and the left channel totally dry and into the tuner.