Today I'm connecting a microphone from our drummer's snare drum into A/D input left jack to process effects for several songs.
We need to add additional process effects for our lead singer, is it possible to connect the singer channel into A/D input right jack and set a different effect for it so each channel will process simultaniously?
No, you cannot split or reroute. Effects will apply to both channels if applied.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
This is a wild stab in the dark.
Some effects allow you to select a single input if required - L or R.
This might help. You'd still be limited. You'd need to check which effects allow input select.
In effect this could give you a separate Left Mono and Right Mono effects chain.
Watch out for the "Multi FX".... some effects have 2, 3 or more "simple" FX included in the box.