"I have my instrument plugged into the inputs of the 828. Why can I only hear it play if I create an audio track and record enable it in Digital Performer?"

Enabling a track to record in DP creates a routing from input to output, which is necessary to hear the source. Until you do this the audio doesn't go anywhere after it enters the 828. This is true of most computer audio interfaces. The software must provide the conduit from input to output. There are a couple of alternative ways to hear inputs with the 828:

1. Using the 828 Control Panel set the Monitor Input to the analog inputs on the 828 you have the instrument connected to. See page 7 & 37 of the 828 User's Guide, on using Monitor Input.

OR

2. In Digital Performer, create an AUX track instead of an Audio track. Set the inputs and outputs the same as you would set the Audio Track. AUX tracks are the same as Audio tracks, but don't record. They simply provide and input-to-output "routing" within Digital Performer.