...Are you referring to the "GM == > Send MIDI Message == > Send XG Mode on Message (Yamaha)" command or the "Auto Send XG Mode on Startup" command?
The Auto Send means that you won't have to revisit the setting every time BB is started up to get the XG sent, and that would be the one I'd recommend using. It is easily turned off in future by simply going there again.
With either one, I get a message that says:
"Yamaha XG users (and others) should likely NOT send this XG on message, and should send GM on message instead, so that drum patches will work. Do you want to proceed with sending an XG? (YES / NO / CANCEL)"
BIAB is telling me NOT to do this, so should I? And if so, which of the two commands should I invoke?
Many of rhe newer Yamaha keyboards can and will run from the standard GM command now, so try leaving it as is first and see if the Drums are working and that the other sounds in the patchlist are what they say they are and not "one off" from where they should be. If anything like that occurs, and your keyboard is playing wrong instruments, try the XG on message.
Also, While I don't completely understand the terminology in the part of your post that I highlighted, I can't route BIAB output from my laptop computer (or ANY output for that matter) into the keyboard because this keyboard has no "Line-In" capability (sadly).
Thanks.
Keyboard does not need the Line INput, keyboard needs Line OUTput to the computer's LINE INPUT.
Some keyboards don't have an Audio Output on them, if so, just use the Headphone output with proper Y adapter to route the stereo to L and R Line INPUTs on your computer.
You can still test and even use BB though, the MIDI sounds will just come out of the piano's speakers instead of the computer's speakers.
--Mac