I just took delivery of an IsoTek Sigmas yesterday in my system... it is the next level up from the Aquarius which doesn't seem to get much love in this thread but I can say it has made a profound improvement in the overall sound in my system - no voodoo here. For $4000 I would be pretty disappointed at even an incremental uplift in quality however it is one of the more substantial audio investments I've made in terms of immediate impact.
For the record with the Sigmas and even with the Corvus I had before, I never had any detrimental effect on the sound from a dynamics perspective. Even when I owned the Corvus for 2 years, I ALWAYS plugged my amps directly into the wall outlet as I believed that any kind of power conditioning would have a detrimental effect on the sound (used the Corvus for my networking gear).
However over the past 6-9 months I have been increasingly distressed by noise and distortion in my system, to the point that I was thinking my hearing had been damaged, because I could replicate it across amps and speakers. For a last ditch effort, I decided to finally plug my amps into the Corvus and lo and behold - I could hear that the distortion was being cleaned up a bit! Not enough that it was gone, but definitely enough to pique my interest on the Aquarius or Sigmas.
The Sigmas has totally cleaned up this noise (which presented itself as echoey/ambient fuzz in the upper midrange of my system, affecting mostly electric guitar and vocal reverb effects).
There is a setting on the display of the Sigmas that can show the incoming THD % of your home power. From every review I have read of the Sigmas, most reviewers state that their THD reads somewhere around 2-2.5%. I was shocked to see as I listened throughout the night that mine NEVER went below 3% and at one point around 10 PM last night spiked at 3.9%. This tells me the power in my house is definitely being affected by the dozens of appliances, wifi routers (we have 4 Orbi satellites), Hue lights, and 2 pre-teen boys with every device imaginable running at all hours. I cannot be convinced otherwise that the source of all my stress and frustration at my system over the past year has been the effect this power has had on my system, audible in the distortion that I could not overcome.
I should mention during that time, I did everything imaginable to tweak out any other possibilities for distortion - I tried many isolation devices, invested in the Naim Fraim, did several Straight Talk sessions with Jim Smith, put in 12 diffusion and absorption panels all around my listening space - every thing I tried improved the sound to some degree but it could not overcome that upper-midrange distortion I was hearing. I even lost interest in listening to my system, convinced I was suffering from hearing damage, or that all my beloved music was victim of poor recording quality (LOL).
I am really impressed with the Sigmas - again I can't comment on the Aquarius but I can attest that the Sigmas restored my system and listening enjoyment, no snake oil no matter how few components are inside the box.