Can I set different MIDI channels for each voice in a Performance Patch?

Not in PERFORMANCE mode. All MOXF Performances in PERFORMANCE mode are addressed on a single MIDI channel. The way it would be done is to copy the PERFORMANCE as a "Template" to a MIXING setup in SONG/PATTERN mode.

Press [SONG] (or PATTERN)
Press [MIXING]
Press [F4] TEMPLATE
Press [SF2] PERFORM
Set the screen so that you are copying the Performance you want to separate Parts of the MIXING setup, you can target Parts 1-4, 5-8, 9-12 or 13-16.
This will set each on a separate MIDI Channel in the corresponding the destination.
Press [ENTER] to execute

This will move the four PERFORMANCE Parts to four separate Parts of the MIXING, placing each on a separate MIDI Channel 1-4 (or wherever you set the target). You can then address them via MIDI on four separate Channels from your external controller.
Name the SONG (or PATTERN) location with the name of the composition.
When backed up to a USB drive in an ALL data file you can always load individual SONGs from any ALL data file (even it if only contains the MIXING setup without any note data) single SONGs can be extracted and loaded from any .X6A or .X6S file.

I am still learning and understanding stuff. I am reading the Understanding Master Mode PDF.

Would you say next logical step after the copy to a SONG/PATTERN MIXING is to use Master Mode to "hold" these collection of MIXING setups?

Setting up the sounds you want to play in a MIXING setup where each Part is on a separate channel is the first step.
If you wind up with several of these MIXING setups then the best way to organize them is Master mode.

If you haven't done already, you should also go to UTILITY mode and switch the MOXF from USB mode to MIDI mode to connect your second board to the MIDI-in jack of your MOXF.

Reiner wrote:

If you haven't done already, you should also go to UTILITY mode and switch the MOXF from USB mode to MIDI mode to connect your second board to the MIDI-in jack of your MOXF.

Actually, no additional setting is necessary. The 5-pin MIDI jack always receives MIDI (whether set to MIDI IN/OUT = USB or MIDI. You only need to make the setting when the the USB "To Host" port is actually connected to an active computer. Then, and only the must you define "where" MIDI data arriving at that port is going to be sent.

If no computer is connected via USB the MIDI port is a MIDI port (you do not need to make any setting). Just FYI.

"The 5-pin MIDI jack always receives MIDI (whether set to MIDI IN/OUT = USB or MIDI."

What if you want to use both a Computer (for Cubase) AND a midi controller with two midi channels for practicing live material. In Pattern/Song/Master mode channels 1 and 2 would still respond to the KEYTAR while the USB mode connects to Cubase?

What if you want to use both a Computer (for Cubase) AND a midi controller with two midi channels for practicing live material. In Pattern/Song/Master mode channels 1 and 2 would still respond to the KEYTAR while the USB mode connects to Cubase?

The MOXF can act as a MIDI Interface for an external device so yes, this is possible.