As others have said - use audio in. This is especially true for loud shows.
You probably already know this, but one thing to look out for - the "audio in" & "mic-in" options will pop up when you plug the 1/8" cable from the Baby Nbox into the A10. The default when it pops up is "audio-in." Just be careful it doesn't somehow get set for "mic-in" because at a loud show, you will overload the A10, and no amount of reducing the input will help. In other words, you can go as low as 1 on the input, and it will still be overloading.