In the words of Old Blood Noise Endeavors:

The second addition of the OBNE Utility Line, the classic AB/Y Switcher. It’s simple: sometimes you need two outputs, sometimes you need two inputs. And then you need to switch between them. Or use them both at the same time. That’s it. It’s not magic. It’s not revolutionary. It’s a simple tool. A tool that you can now get from Old Blood.