Here's my 2 cents on this topic.

I used to have a Korg D-1600. I didn't like it and sold it a few weeks after I bought it.

Personally, I'd go the other direction. Record the audio in the D-1600m because it actually does that fairly well. Export the wave files to your computer and drop them into REAL BAND. Import the drums and whatever else you need from BB and mix them in the computer using RB.

Transferring files is simple. You select the export file function and select a destination. Drop and drag often works well. Once the cable is connected, you should be able to see the computer from the D-1600 and vice versa. Follow the menu on the D-1600 to export or import the files.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.