The Epicenter restores bass by using patented technology to analyze music, find higher-frequency harmonics (like those around 100-350 Hz), and digitally recreate the original, missing low-frequency notes one octave lower, injecting them back into the audio signal for deeper, more impactful bass without just boosting frequencies or muddying the sound.
As a comparative, years ago, Pioneer patented a process called Lagato-Link for doing essentially the same thing, on their Elite CD players, except it was to recreate and reintroduce upper harmonics cut out by the absolute 20- 20K limitations that many of the first CD players had.
Both of these technologies use a digital algorithm to create the effect, which is delivered through analog outputs on both the Epicenter and the Pio units.
Interesting side note, the effects are lost when using the Pio's digital output.