I have been using my HP-507 as a simple midi controller for Logic, and then playing back through amplified computer speakers. But I accidentally noticed yesterday that a recorded track came back through the USB cable and I heard it through the Roland! Did I just imagine this? Or am I missing some configuration? I can't reproduce this. The Mac does not show the Roland as a "core audio" device so I can't select it from OS-X. Does anyone know how to configure Logic/Mac to playback through the Roland audio system with the USB connection?