Another method would be to render the track to a WAV file (Right-click, Track Actions, Save Track as WAV File), and save it in the same folder, with the same name as the song file. If the song is Song1.MGU, call the WAV file Song1.WAV.

Then re-open the song, and that WAV file will automatically play on the Audio track. No importing required.

Thanks
Kent
PG Music