While I am at it - power cords. Feet. I am sure they do make a difference, but it is rather small, compared to other things, in my system, starting from a solid stone rack where the feet don't make a big impact. Larvikite (Norwegian) stone. So for example my Hanss t-30 player rests direct on the top stone shelf, but then again, it has maglev feet. I've damped the shelves a bit, on the low/back side, to avoid vibrations, and I cannot feel much, using the "very light finger touch" test, nor do I hear it, with a stethoscope. The vertical space between the rack shelves is too small, to use high feet / footers beneath the Io control unit. I value good air conditioning / breathing space for the unit more than the last word in damping, although Aesthetix would say that the Io sounds even better with HRS feet, I think. Maybe I can think of other ways to dampen the units a bit more - I have the old (black) chassis version, which is why my Eclipse upgrade is "partial". Suggestions welcome. But all in all, it seems that in my rack, it is quite well situated, on its "bare" factory feet.
What about power cords? I am sure there is a difference. But again, the biggest difference in my system was installing a separate power course, instead of the "lamp" course in our living room. This made a huge difference. The power cords (at the end of this course) also make a difference, at least, going from stock cables to something better. How much better? Not sure what is needed. Not easy to test, since my rack is back to the wall, and changing cables and cords is a lot of work, not good for my prolapsis back. So I tend to stay with a "good enough" experience. Within this, however, there is a ranking order - yes. The Shunyata Taipan helix performs well in my system. Maybe my best power cord. A Wyrewires Juice 2 does the job also. PS audio Perfectwave AC5 also quite good. Better than stock cords. Supra lo-rad is also ok but less so, it is in the middle, comparing my best cords to the stock cords. I like JPS cabling in the rest of my system - interconnects, speaker cable - but have never tried their power cords. Note that these are my listener preferences over time, using the cables with different components, not especially tested with the Io.
Same thing with feet. I only have a rough estimate. My alround best are probably Cerapucs, but they make more difference under the speakers than under the Io, so that is where they stay. The next best are probably black ceramic cones (worked well under my former VPI player), but too large to place under the Io, in my rack. I find that with a turntable that needs better vibration damping (like my VPI Hw19), the feet plays a large role - but with other, fairly well-footed components, not so much. But like I said, I have not investigated much.