Put the driverack in the same rack as the AR2412 on stage. The outs on the AR24 are assignable; assign one as mainL and one as mainR and plug them into your driverack inputs. If you want to keep the driverack with the qu at the rear of the auditorium, you’d have to go out of the QU mainLR sockets into the driverack, then go out of the driverack back into a spare channel (or 2,) on the Qu, then route the direct outs from those channel(s) to the AR2412 outputs, then feed your amps from these outputs. Doing this negates some functionality of the driverack though. Instead you could run a couple of XLR cables alongside your cat5 cable between the Qu and the AR.