Dist 'SYM' control ? Noise floor panning

Can somebody explain a bit more about what this actually does ? Does it effect which part of the sound gets distorted ?

I’ve noticed turning it to quarter past can kill unwanted noise floor in certain sounds.

Oddly over headphone I find turning this, or the Comp’s ‘mix’ encoder can make the noise floor introduced pan left or right.

What is going on there?

This is over headphones btw, you may not hear it on monitors.