@Jack said:
Hi @[deleted],
You can’t I’m afraid, the best route to go is to mix your instruments before they get to GTL then you can record any instrument to any loop. I prefer an external analogue or digital mixing desk, preferable one with a usb interface so you can connect straight to your device. alternatively you can also use a third party app like AUM to mix your instruments into GTL.
Keep an eye out for GTL pro, I’m working on it now and will do exactly what you’re asking.