OS 3.0
Under the new OS 3.0 is it possible to assign the Montage A/D input L/R to a track in the new sequencer so that a mic can be used via that input to add vocals to a track/sequenced project?
No. The Sequencer tracks record MIDI data, only.
The germ concept behind the Motif-series synthesizers (2001-2016) was to combine an audio sampler with the MIDI Sequencer (called the ISS, or Integrated Sampling Sequencer). This was accomplished by “sampling” as opposed to just recording audio. Samples differ from regular audio recordings in that a sample can/must be triggered by a MIDI Event, so the audio is ‘cued’ to play on demand. When used, the Integrated Sampler, automated punch in and punch out to correspond precisely with the Note-On event in created at the punch-in point and created it had a Gate time (duration) to precisely correspond to the audio end point. Efficient.
So the Sequencer still only recorded MIDI events, those MIDI events were used to cue the sampled audio to playback... as long as you did not change the original tempo the audio synchronized perfectly with the synth MIDI Tracks. If you wanted to adjust the tempo after recording audio, the Motif-series would be able to “slice” the audio to expand the range of useable tempos.
During that fifteen year period (the Motif Era), sampling, time stretching, pitch correction and other tools to adjust the audio recording has improved to a point where you'd have to ask why do it any other way than with your computer. With tools like Cubase Pro (the upgrade version of Cubase AI provided), you have unprecedented tools to manage and mangle audio.
See this short video as an example of why Cubase Pro is ideal for audio recording and manipulation — here shown is creating audio harmonies:
What you can do with a MONTAGE or MODX
The new synths feature a quality way to get audio from the real world into your music production sphere. The A/D In and the processing you can do to this incoming signal allows you to deliver pristine audio quality to your DAW (like Cubase). They do not feature a “sampler” so you cannot record audio directly to the internal sequencer.
__ You can record both the MONTAGE and a live incoming A/D Input to a USB stick... example, if you play and sing, you can record yourself to a USB stick as a stereo .wav file.
__ You can create your synth MIDI tracks using the MONTAGE internal sequencer... then drag and drop the results to your favorite DAW, where you can now use the MONTAGE as the audio front end for the computer... record your A/D IN through the MONTAGE utilizing its boutique grade processing to your DAW.
If your end goal is to take these audio tracks with you to the stage, you can. You can export the audio from your DAW in .wav format. They can be loaded to the MONTAGE/MODX as a New User Waveform - you can Assign it a Key in a Part and you can trigger its playback via a MIDI Note-On event.
By integrating the MONTAGE with the computer for audio recording, the MONTAGE is freed to be what it does best, be a synthesizer; and it becomes is the next logical step...32 audio bus outputs via USB means you can record individual outputs on everything.