Recording in Acid Pro 5 (by 2 users)

Are you plugging the instrument directly into the computer? If so you only have mono jacks from your bass, guitar so on and so forth! So in channel in only one to record! Try using a stereo microphone and record pointing at the amp. That way you will get stereo through your device. If that is not the problem make sure that the settings on the Prosonus is set to output stereo. And for most check all your plugs to make sure they are stereo inputs and outputs.