I have a TC Electronic G-Force and Eventide Eclipse in the parallel effects loop of my amp and use a rack mixer to keep them in parallel with each other, and so allow me to use them both 100% wet and so avoid having to digitize my dry signal. I do have OCD about keeping my core dry signal out of the digital domain completely.
But I also have an Eventide Pitchfactor and would like to put this in too, and although the rack mixer can accomodate 4 in and 4 out, adding the Pitchfactor to an already limited rack space would be a pain, so I wanted to make a little 3 channel utility splitter/mixer to use instead of the rack mixer to save 1U and allow me to put two pedal trays in my 6U rack.
I used the splitter scheme you can see at Paul in the Lab, and a generic mixer circuit I found so that everything can be done with one quad opamp. I may even make this with 3.5mm jacks for the send and returns, make up my own high quality cables and then this will all fit comfortably in a 1590B. It would pretty much be a set and forget utility for me so I suppose I could even use trimmers instead of pots, set the levels and tuck it away somewhere. So I thought I'd add it here and it may be useful for others to adapt for their own uses.