Its connected Left only in the loop of my Boss GT-10. I switch that loop between series, direct out and parallel, depending on what sounds I make. Parallel (Direct Mix) is actually my most used method, though Direct Out is useful when I only want to hear what's coming from the Eclipse (such as a guitar sound made solely on the Eclipse). I don't use series very often. My GT-10 goes straight into my multitrack w/headphones. I have an amp, but have only used its series loop with my GT-10, not the Eclipse. I use the optical in and analog XLR outs when using the Eclipse with my multitrack (synth tracks in particular). I will eventually start using the Eclipse on vocals. I tested it on a film, and you can do some trippy stuff with it.