PG Music has a "MIDI In a Nutshell" Tutorial that addresses this issues better than I can:
https://www.pgmusic.com/tutorial_midi2.htmThe important point is that MIDI itself has no sound, so poor MIDI sound quality is a function of the synthesizer it is played through. Chances are that your DAW has a better quality synth than whatever you're playing BIAB through.
Oh, and welcome to the forum!
Bruce