thanks for your replies, they have been very helpful!
im using my laptop with a midi keyboard to trigger samples or synthesizer bass sounds. running in mono is no problem for me on stage.
i havent thought of the ground loop noise issue … could plugging it into a di box with a ground lift switch help to avoid them? (i have no idea of electricity, but i had issues with noise on stage once and the technician plugged my cable into a di box and the noises were gone)
if that's the case and i can tell the pod unit to send the bass signal through the left output and the (uneffected) laptop signal through the other output that might be a good solution for my problem