I am interested in understanding the functional objectives of the feature and a description of the changes that the feature brings to the input source. I realize that it enhances the sound from a small set of laptop speakers but when played through good quality headphones, it's clear that the application is making many changes.
Fidelity deals with ranges within the spectrum separately and compensates for what is lacking in energy for that very audio signal. This makes the sound feel crisp and bright to your ears.
Fidelity has been designed to faithfully reproduce a more accurate version of the audio recording.