G'day Zen, a magician never gives away their secrets.
A combination of elements were used, Isolation and ferroresonance selectively tuned so as not to be a current constrainer.
Like all forums and internet talk I would
never lay claim to being an expert and can only guide people to what I have experienced in 40 years of audio passion.
If people wish to improve their mains feeds within their homes then they
clearly should use an approved electrician to do so, this way they will not infringe any dafty local bylaws which were probably copied from some one elses where conditions are considerably different.
When you look at some of the adult sized mains cables plugged into some feeble noise generator of a socket and the 20 year old wiring leading back to a dusty box with ELCB's or fuses green and aged it comes as no surprise that this situation can be improved. Those with monster Krells will attest to the requirement for a better mains feed pays dividends, less obvious with more run of the mill gear.
I posted reference to Ben Duncans articles and he is regarded as 'expert' in that he is a leading industry light when it comes to electrical distribution within studio and live sound. For expert advice read his articles, I did many years ago.
Have you managed to overcome the issues surrounding the implementation of Zen clocks yet? MY CD94 is still panting!