So I'm trying to figure out Guitarix but I'm stumped. Part of it is a lack of time to futz with it and part of it is just ignorance. So here is where I am. I'm using a presonus audiobox usb. In the Jack setup, it's the hw:USB under interface. In this image, you should be able to see the layout. When I go to connections in Jack, I don't see Audiobox in the Audio section. Only in the Midi and Alsa sections, but both of those say Midi and that's not what I want.