The X81Z will work with BIAB just like any other MIDI compatible hardware. It does not have usb connectivity and requires a MIDI to USB interface.
However, it would not be a very good choice for BIAB for several reasons. It does not have a GM mode and it has only 8 note polyphony. In performance mode, it becomes multitimbral, but the 8 note polyphony is shared. Theoretically, 8 sounds can be programmed, but each would be monophonic. Drums would also be a difficult task. The best BIAB useage would be as a MIDI sound source for only one BIAB channel such as bass, piano, etc.

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