MIT Z Stabilizer ll ? operation ??

Actually, I would appreciate the same answers, as I too, own this unit and have noted sonic benefits but have absolutely no idea how this unit would work.

Your kind words are gratefully accepted! The key to MIT Stabilizers, in general, is less about filtration (although they do an excellent job) and more about Power Factor Correction. In residential AC, the Voltage component and the Current component are rarely in phase with each other. This makes usable power LESS available. The ratio is called Power Factor. In Power Factor Correction (PFC), the Current and the Voltage are brought more into line with each other, and, therefore, the power transformers of your system "see" more available power. PFC has been used in the industrial world _almost_ as long as AC has been available. Bruce Brisson was (is) a pioneer in using PFC to improve the performance of residential (and studio) sound and video systems.
Hope this helps. Joe

So, is it compensating for inductive or capacitive loads, or both? Does it have a bank of capacitors or an inductor (or both or something else)? Mine (bought a LONG time ago), has a toggle switch, presumably for different conditions (current leading vs lagging) but no way to determine which position to use other than setting by ear. Is this the case with all models?

Thanks for your input Joe Abrams. Your comments on power factor correction make complete sense as the dynamics of the music are certainly improved with its use. However, in addition, I'm experiencing very significant improvement in the clarity, detail and deeper view into the orchestra which I have determined is due to its ability to reduce noise and distortion from the incoming AC noise, and isolate digital hash as well. MIT says the filtering action is done "in parallel" to the AC power. I would like to know what components/technology are used, and if internal components upgrades might improve this aspect of its function. These are old units so I can't imagine there are any "secrets" about it.

Larryi, it sounds like you have some knowledge in the area.(inductive or capacitive loads- is like Greek to me)
You mention yours has a switch-which means it is the older 1st series. Have you the ability to peak inside and perhaps discuss your findings?