The stereo settings are included with each profile. So if the profile contains settings with stereo enhancement on, it will turn on automatically when loading that profile.
The FULL version will allow dragging the circles to change the amount of stereo enhancement.
This stereo effect is for speakers only. You can hear the effect clearly when in Movie Mode and you are using speakers that are close together like a Jawbone Jambox.
You will see it is disabled for headphones. However, you can turn it on for headphones to create a mono effect so it is more comfortable to listen to old recording where the drums may be in one ear and the voice in the other.