I’m looking at them now.
The Length of Filter affects the quality or stiffness of the filter. This filter skates very close between sound quality problems and suppressing noise. A high length value helps it along.
The -6 value is for shooting live sound. It was chosen so as to produce a high value, good quality show but still give a little “elbow room” for theatrical vocal expression. ACX specification is -3. They’re not shooting live any more. Their concern is to have all their works match each other.
FAR above the -6.
Open the show in Audacity and turn on View > Show Clipping. If your timeline fills up with red bands, you’re dead (attached).
That shows unrecoverable distortion.