http://www.cakewalk.com/Tips/April03_AndertonPt4-reason.asp
From the above link......
APPLICATION #5: USING MULTIPLE REASON OUTPUTS IN SONAR/HOME STUDIO
This is an advanced application that lets each Reason instrument output show up as a separate SONAR/Home Studio track, rather than feeding them all into a stereo mix. Therefore, each instrument can have it own audio processing in SONAR/Home Studio, and track data (level, pan, effects send, etc.) can be automated within SONAR/Home Studio.
Here's how to set up SONAR/Home Studio & Reason for multiple outputs.
1. When you insert Reason as a ReWire device, uncheck First Synth Output (Audio) and check All Synth Outputs (Audio).
2. SONAR/Home Studio inserts Reason and then creates 64 tracks - one for each audio output in Reason.
3. Use Reason's patch bay to connect the instruments in your Reason rack to the desired outputs.
4. To simplify the Track View, hide tracks that correspond to unused outputs (while in the Track or Console View, access the Track Manager to show/hide tracks with the M keyboard shortcut).
For example, suppose you've set up a Reason rack with 2 Malstroms, 2 SubTractors, and 2 NN-XT samplers. Reason outs 1 and 2 are tied in stereo; the rest are mono. We'll assume there are no other tracks in SONAR/Home Studio except for those that represent ReWire instruments.
In most cases, each stereo instrument will end up using two of the mono inputs and take up two tracks. You might patch the instruments as follows:
Malstrom 1: Reason Outs 1+2 (appears over SONAR Track 1, which is stereo)
Malstrom 2: Reason Outs 3+4 (appear over SONAR Tracks 2+3)
SubTractor 1: Reason Out 5 (appears over SONAR Track 4)
SubTractor 2: Reason Out 6 (appears over SONAR Track 5)
NN-XT 1: Reason Outs 7+8 (appear over SONAR Tracks 6+7)
NN-XT 1: Reason Outs 9+10 (appear over SONAR Tracks 8+9)
You can now hide (or delete) all Audio tracks in SONAR/Home Studio from Track 10 on up.