I'm experimenting with the vocoder right now. It's very much fun to play with. I. e. take a piano and have a brass section follow your voice, especially a mute Tp/Tb section is very nice (ok, piano and brass on the same midi channel)
I set up a small song for testing and recorded my piano play (vocoder carrier) and my voice (vocoder modulator). During playback I wanted the vocoder to respond to the recorded audio, but sadly, I couldn't route the output from audio track 1 directly to FX ctrl. bus 1. As a workaround I had to route the audio track to an empty IFX slot, set the normal output to off (I don't want to hear what I sang) and the ctrl. bus to 1 (the vocoder's modulator bus setting). That worked as expected and was very much fun to play with.
But am I missing here something? Is it really so that I have to "waste" an empty IFX slot for this routing problem?
! Don't know why I overlooked this