Thanks! Sure there are ways .. To clarify confusion: It's centered around a drumset, which delivers most mics into a 12mic which is connected via madi usb to a windows computer running cubase. Cubase Mix goes back by madi into the 12mic, out via ADAT to an ADI 2pro, which serves the drummer as headphone amp. Now the Helix is on the opposite side of the room, feeding a 112 cab via a Freyette PS-100. The cab is mic'ed and the signal fet back to the 12 mic and is added to the mix in cubase.
Now I want the guitar player to hear the final mix. Sure I can send it over in all kinds of formats (the Adi2 can do so) and digital would be best. So I thought it was convenient to use the spdif in of the Helix to serve as an headphone amp for the guitar. By now the mix goes via RCA to a seperate headphone amp which provides the mix for the guitar. Using the helix would probably improve signal quality (digital) and it's one device less.
Hope this helps (but might even increase confusion :-))