Yes you can! Please not though that if you’re using Windows Vista, all audio from WIndows that is passed on to Balance may play back at the wrong speed if you’ve set different sample rates in the ASIO-client (Reason, or any other audio application) and the Windows audio settings. The workaround is to set Windows to use the same sample rate Reason does.This problem doesn’t occur if no ASIO client is open.
On Windows XP, the same problem might arise if you start playing back Windows audio (Spotify, iTunes etc) and then change the ASIO sample rate. The workaround for this would be to stop the WIndows audio playback, just to start it again. Now Windows will use the correct sample rate.