I am using BIAB 2020 for the Mac, with a Yamaha PSR-443 keyboard connected via USB. I have MIDI IN set to Digital Keyboard and all ports set to MIDI Plugins. I want to play along with a song and record audio and/or MIDI. The problem is the volume on the THRU track. The track slider does adjust the volume, but even set to 127, the keyboard sound is barely audible above the rest of the playback. I did go to Preferences/Normalize MIDI velocities and changed it to 127. Not much difference.
I also tried a Griffin iMic device to take the audio from the keyboard and feed it to BIAB via USB in the Audio Devices window. Not much louder. I see it is possible to set other tracks to a lower volume but this seems like a clunky workaround. Also, in many cases, I am working with an imported MIDI arrangement, where the track volumes are determined by MIDI and can’t be changed with the volume sliders.

If possible, could you do a short test MIDI recording using your Yamaha, save the file, and attach it to your reply to this message? You can use the 'file manager' to attach an .MGU file (Band-in-a-Box song).