I'm thinking about using biab for gigs but have a problem: I have some singers that come up and want to do a song in "their key", not mine. On my keyboard, I can easily hit a button to do that, while I play the chords I'm used to and see on my charts.

If I use biab, I can't find a way to transpose the sound without changing the chords guiding me. I know I can change the display without the sound in the notation window. And I've changed the key with transposes the sound and display. But no way to just transpose the output!

Also, regarding changing the key signature: What is the effect of changing the key signature without transposing? I was thinking that it would affect the display without the sound output, but it doesn't appear to do anything except just change the key signature.

How do other players handle transposing the sound output?