I mostly use my PODxt pro for home practice through headphones. I've been trying to puzzle a way of playing my digital metronome through the unit so I can hear the tempo 'beep' as well as the guitar signal. I assumed I could plug in the metronome using the appropriate cable to the red and white s/pdif connections on the back but I still couldn't hear any 'beep' so now scratching my head wondering is it possible at all? Or am I already correct using the red and white sockets but there's a volume/on-off level relevant to these that I haven't discovered yet? Any help would be grateful!!!????