Bass Harmonic Enhancer — adds 2nd through 7th harmonics to your low end while keeping the highs clean.
SPEC button in the top-right of the display.
+6 dB to start, then bring up just the 2nd harmonic to around 30–50%. Listen to how it fills out the sub. The 2nd harmonic doubles the fundamental — great for making sub-heavy basses translate on smaller speakers. Once you have a feel for it, start adding the 3rd for grit. Even-order harmonics (2nd, 4th, 6th) tend to sound warmer and more musical; odd-order (3rd, 5th, 7th) are grittier and more aggressive.