Use different high-pass filters on the left and right channel

Dan Worrall uses one 12dB/oct and one 24dB/oct high-pass filter on each channel. The result in mono is a slightly higher tuned high-pass filter. This is useful for something like a guitar, which could use some low-end without conflicting with the bass. The result is some low-end that is spread to the sides, out of the way of the bass.¹

I have a setting in Volcano 3 that emulates different stereo tolerances.