Alright, so I have Reason 3.0 running with Digital Performer 4.6. The problem I have is the only way I can get notes to sound in reason is when reason is running by itself. Even when I open an mp3 in quicktime and try to play the keyboard on top of it reason will stop sounding. You can see on the reason mixer that sound is coming through it is just nothing is coming out. Any suggestions? I am using a powerbook G4 laptop and I am using the headphone jacks for my sound output.

First off, you can go into the audio section in reason's preferences and click "play in background", this should let you play along with a mp3 in quicktime. In digital performer, go to the reason plug in, and make sure that the box in the center is set to "Mix L R" or something like that. Hope this helps!