The Koen Heldens Signature Series adds the KH-EQ1, a semi-parametric equalizer that covers 20Hz to 33kHz in five overlapping bands with 18dB of boost/cut for each band. Uniquely, for each individual EQ band, you may add harmonic color and saturation separately. Especially suited for stereo sources, the KH-EQ1 has a variable Mid/Side processing mode.
You can tell an actual working recording engineer had a hand in the design of the KH-EQ1 because of a feature called “Auto Listen.” When enabled, clicking on any of the five EQ bands' frequency controls causes that band to solo and fully boost at whatever frequency you have selected. While clicking down on the frequency control, this works smoothly for instantly fine-tuning the Freq knob to find the “sweet spot” frequency for boosting or cutting. Love it!
I also thought the Mid/Side feature was done in a unique way. It is always available and continuously variable. The default is the Stereo Mode control knob is straight up at 12noon and whatever EQ you have is equally applied to both the left and right channels conventionally. For stereo backing vocals, guitars, or music tracks, the ability to equalize the phantom center to shape element(s) placed there without affecting the L/R Sides is brilliant. Conversely, it is easy to brighten up the Sides for enhancing the stereo width.
I liked this feature for drum overheads to either play up or down the cymbals on the L/R pair or play down the snare drum in those mics.
Lastly, the per-band saturation is slowly growing on me and, so far, I like it as a “tonal coloring tool” for throwing very clean tracks in the dirt to rough them up, but only in certain frequency ranges. Fun stuff!
With all presets included created by Koen himself, Black Rooster KH-EQ1 5-Band Semi-Parametric EQ Plugin sells for $59 as a download.