Hello,

I think the easiest way for you would be to go 1/4 to your interface and switch your XT Live to a Studio out setting. The USB works great for track recordings while using the Headphone or 1/4 inch outs of the XT Live for monitor but I am not too familiar with Cubase. I use mine with Garageband. XT Live IS my interface as the signal comes back through my outs, however in Garageband as with other DAW applications as well, there should be a Audio Setting that will allow you to change what input and output device you would like to use based of what is actually connected to the computer directly. Hope this helps.

Good Luck!