I am wondering if I cant set up the Mic input to infact superimpose voice onto the Synth (not vocoded).

Reason is I want to add Audio instructions and notes to an Idea I recorded.
It is very important to capture the meaning of ideas on the fly.
It is a drag to always have a Daw enabled mic in a separate channel. Having a Mic through The XS makes things rugged and immediate.

Here is a post I found on another site

I’ve only tried using the XS vocoder a couple times, but it is quite impressive.
You however need a PhD in menu diving, which is why I made the following cheat sheet which may help:

YAMAHA MOTIF XS CONTROL SETUP

VOCODER MIC
[Utility]
I/O >
Input: mic
Voice Audio > *Output* >
Mono/Stereo: L mono
Output Select: ins L
Control > *MIDI* >
Local Control: on
[Store]
[Voice]
(Pre 8) > (H) > (13)
(Pre 8) > (H) > (14)
(Pre 8) > (H) > (15)
(Pre 8) > (H) > (16)

[] Function button
() Program button
** Submenu

How would the above setup change to have voice superimposed or mixed in with the synth output ?

See http://www.motifator.com/index.php/support/view/setting_up_a_microphone_motif_xs

Additional notes…
1) The mic has to be a dynamic type. The A/D INPUT is unbalanced, so the plug on the mic’s cable needs to be TS (Tip/Sleeve) type, not TRS (Tip/Ring/Sleeve).
2) With the Utility mode Mic/Line setting at “mic”, and the rear panel GAIN control at max, if the mic level still isn’t sufficient, the A/D Input “Volume” can be increased from the default of 100 to as high as 127.

Thanks a lot.
I now see I already configured it like you describe that for another project long ago. Gets confusing.
But thanks, solved it!