MIT Z-Stabilizer - original with two-way switch on front - anybody know why two settings?

There is clearly a difference in sound when you switch between settings on these funky old units. Anybody know what is the technical difference between the settings? Seems illogical to choose between, "clean power" vs "even cleaner power"?
I have 3 of these and find them useful. The switch as I remember adds "damping" to the line. I don't know about it but  perhaps Joe Abrams can clarify. I have found the position where the rocker is pressed to the left is always better in my system. They add value in my reference Spectral/MIT system.
Thanks so much for the response ptss. I have unearthed my 3 Stabilizers which I haven't used in years since a major move and now regret so as the improvement is quite audible in my EAR/Croft/Cary electronics. So I'm sensing they rpovide a selection between 2 "different" forms of applied resonance, as opposed to "more" or "less" applied resonance.
What do you mean by 'resonance"?
There are Audiogoners far more technically savvy than I to answer ptss,  so hopefully they'll chime in. All electronic devices resonate. They all vibrate to some degree apparently. Putting "dampers"on vacuum tubes to reduce "microphonics" vibrations which surprisingly impacts the electrical performance and therefore the sound being maybe the most understandable form. Old tube gear came with shields that the tubes were cocooned in. Maybe the resonance in transformers which you can actually hear despite no intentional "moving parts" maybe the most obvious. Power cords apparently resonate too. VansEvers told me that the switch settings for the two switches on my CleanLines Jr 11-Analog which my Basis motor is plugged into, "does nothing electronic, just changes resonance". Noticeably changes the sound. I think the Z-Stabilizer provides parallel circuitry to whatever is plugged into the same power receptacle which apparently damps that resonance. Okay, somebody else please respond as I could be all wrong.