Using a ReWire application in conjunction with your main DAW can offer powerful benefits. For example, Propellerhead Reason can serve as a flexible, highly CPU-efficient sound module for your MIDI sequences. Making this work in Pro Tools 7 is easy.
1. Launch Pro Tools (LE or TDM)
2. Launch Reason (or any ReWire-compatible application you want to run on the same computer, such as Live or DrumCore.
3. In Pro Tools, create an Aux Input track (mono or stereo, depending on what your ReWired application will be sending out). Instantiate the ReWire plug-in for your application. (You'll usually find these in the Instrument plug-in category.) In the ReWire plug-in, select the audio outputs from Reason (or your other ReWire app).
4. Create a MIDI track. Assign its output to your ReWire application. For Reason, there will be a channel available for each module you have installed in the Reason rack.
You're all set! Now Reason (or your other ReWire app) will be synced up with Pro Tools; when you play Pro Tools the ReWire app will follow along. You can send MIDI to Reason to play its instruments, and you can monitor the Reason audio output back through the Pro Tools mixer. You can even apply plug-ins to process the output of your ReWire application.