When BIAB plays a MIDI trumpet part, it sounds like a trumpet.

How is this working, on a Mac?

As I understand things, BIAB is invoking CoreMIDI, which must be using some particular General MIDI sound bank, or sound font, or whatever it's called, correct? If so, where can I specify that? How could I use a different one?

In Logic, there is an instrument called "DLSMusicDevice" that uses Apple Sound Bank Synthesizer to point to a Sound Bank named "QuickTime Music Synthesizer". Is this what BIAB is doing also?