@Charlie Tuna sent over this here:
Broughton calls it the Filter FX Loop, but I call it the Dirt Fixer.
It's a simple FX loop with a clean blend.
Only that it also has a phase flipper and LPF/HPF on the wet signal plus a LPF on the dry signal.
I tried it out with the Sushi Box FX Fluffy Kitten, a pedal that I bought when it was released (I got one of the very limited first run), but quickly decided that it does not really work with bass because even with the bass knob maxed, there's a lot of low-end-suck.
The Dirt Fixer takes care of that in a very good way. Both low pass filters are extremely helpful.
When you cut most of the treble on the dry signal, it blends seamlessly and there is no audible separation between the two. The wet filter can take care of the top end, should you dial it in too harsh on the pedal in the loop.
I only got as far as trying a single pedal in the loop, but I'm curious to try it with a synth chain, maybe even an octave going.