Have not been able to successfully use Logic 8's I/O insert (under Utilities) and wonder if maybe I am obtuse, or Logic is recalcitrant. My workaround works, but I wonder if the I/O insert utility is junk. I can hear my external reverb by creating a "send" in a rhythm guitar track, which creates an aux channel in the mixer. It works when I cable an output to the external reverb "in", and then bring the reverb's output back to my audio interface's in. In this case, I am using my output 49 and returning to input 49 (most of the first 48 interface channels are ADATs, 49 is my analog-in of choice). I set the Aux input to the bus where I sent the signal from the rhythm guitar track, and then set the Aux output to the 49-50 output pair. 49-50 get mirrored to the main outputs by the hardware. So these connections are active and functional. Alternatively, I can install one of Logic's software reverbs into the Aux insert slots and that works okay, with the Aux output set to either 1-2 or 49-50. I can even hear both internal and external reverbs with the output set to 49-50. But I can only hear the internal reverb with the output set to 1-2. I have been unable to get the Utility > I/O plug-in/insert to work following the instructions in the manual. So I have a work-around, but now I wonder if this is a bug, or if I misunderstood the manual. Any help from users of the I/O plug-in most welcome.