The Aural Exciter extends the high frequencies, unlike EQ’s and other brightness enhancers which only boost the high frequencies and alter the overall tonal balance. The stereo image is enhanced with the Aural Exciter, resulting in a greater perceived loudness without an introduction of noise into the audio path due to increased gain. Vocals and instruments seem to stand out, without raising individual volumes in the mix.
Big Bottom circuitry dynamically shapes the bass response in the 20Hz to 120Hz range, increasing the perception of low frequencies without boosting the maximum peak output.
Here's a link to the product manual >APHEX<