I've just started using REW and I have had a little success with the above set up. Unfortunately, REW will only recognise the inputs of the duet in stereo pairs - there is no option to select only the one input/output channel either for calibration, levels or room measurement. This leaves me a little stumped. I read that there are issues with REW and Mac firewire interfaces that prevent separate channels being available to select. Is this still the case? Can anyone confirm the successful use of a mac and firewire interface with REW?