Note: this feature is available in the Pro edition only.
Comparing your master with similar commercial recordings can be very helpful. If it sounds similar you can expect your master to sound good on a wide range of playback systems. If it sounds very different you've probably made a mix that sounds good on your audio system only.
You can click the Browse button to load an audio file. If Loop is engaged the file will loop. The Volume slider can be used to make the reference track level identical to the master level.
It often makes sense to play only the chorus of a song. You can load the audio file in a track, select a chorus and export the selected part. This new file can be used as reference file. Make sure the loop button is engaged.
The Reference File plays back mono if the Master section's Mono button is engaged, so you can compare mono versions too.
You can also use this feature if you're trying to make a better mix of a song. First, mix the old version down to an audio file and use this audio file as reference file. Now you can easily compare your new mix to the old one.
Note: the audio files aren't copied to the song folder in order to avoid having multiple copies of relatively large files. Presets don't contain the audio file itself either.
Note: the Reference File is audible only if at least one track plays back audio. Both audio tracks and MIDI tracks using a software instrument count.