Thanks Jim for the suggestions!

I'm thinking now I really should have put this thread into the Songwriting forum.

With a portable recorder like the Zoom (do they still make those, I'll have to look that up)or a smart phone, I'd have to transfer the vocal melodies to BIAB via an SD card, right?

But I'm wondering, if I can record a vocal audio performance into BIAB with a mic plugged into the mic jack on my desktop, how would I render that melody from my voice to a chosen instrument (so that a trumpet or sax or guitar etc. is playing it instead of my voice)? Is that a simple operation, or what?