1. Can anyone think of a reason why my headphones (inserted into the Presonus Firebox) will only play tracks on garageband through my left ear? Same happens with different headphone sets. I can't find any advice on this in Gavenda's book or Garageband help or the Firebox manuel. 2. I plugged my ordinary 4-year old Dell computer speakers into the Firebox Main Line-Out socket but no sound. Do I need special speakers? Thanks for any feedback.