I suggest you may have a better and certainly a much cheaper option by continuing to construct your songs in BIAB. "I should like to construct my music "one track at a time" - or, with BIAB, backing track then add more than one "lead or harmony" track from my Tyros 5." is something BIAB can do. There's no need for moving to any DAW or multi track hardware device unless your recordings become much more complex that what you've stated.

BIAB functions as a Multi Track Recorder and can create very complex arrangements of either MIDI or Audio files or a combination mixture of both types. A BIAB song can be comprised of dozens of MIDI Patch changes, dozens of RealTracks Audio, live audio recorded into BIAB and any combination of these various inputs onto dozens of tracks. Once you learn the steps to do this, you can experiment and audition techniques without any limitations.

You can use your Tyros 5 as an external synth directed by BIAB's chord sheet and BIAB Style and record it.

BIAB can record the output sounds of your Tyros 5 (which you already know)

Audio is simple to record and you only have to learn the one simple trick to "sync" recorded audio to your BIAB song to gain full advantage and use of it.

It seems learning more about BIAB is the simplest and best method you have available to simplify your musical path and allow you to enjoy your music while getting the most from the equipment and software you already have.

BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.