My old QED switch box, like the ones I have linked to in my earlier post, do allow you to set Input 1>2 or 2>1, so you could record from one source to another. You should then be able to set your BC9300 to a difference source. I never actually tried that myself when I had one of those switch boxes, but I see no reason why that wouldn't work.
Location: Liverpool
My B&O Icons: