I use a separate mixer (Sonar/Roland VS100) for my mic and my wife’s mic. FX... Comp... EQ.

On the PA4X, I used the mic once in a while. I would set my volume and leave it. To control balance of my mp3 backing tracks, I used the assigned slider. To control my R1 sound, I would use the slider. I set the main volume and leave it.

For bigger gigs, I would split my mic with the radial MS2... one to the Pa4X... one to the mixer... and one to my Roland VP-7. Then I have 2 harmonizers and one normal mic signal. It gave me choices and the best of all I had. The VP-7 is a great harmonizer... especially when I want a choir type of harmony.