Most satisfying system change in 2017?

I moved part way across the country earlier this year, few changes to the basic system components, but:
1. room- longer, deeper room, with slightly higher ceilings;
2. new power subsystem based on a 10kVa Controlled Power isolation transformer
3. I installed a big Minus K under the turntable- a heavy Kuzma XL with HRS platform to isolate the table
4. I added new subwoofers- a matched pair of 15" Rythmik sealed boxes with a small DSP controller.
I did not do this incrementally, so the changes in the aggregate were significant though for about a month, waiting for the Controlled Power unit to arrive and get installed, I played the system without it-- the power here, even without the isolation transformer is better than it was in the New York metro area, probably due to newer infrastructure. Density is actually higher where I am now, in central Austin, compared to the Lower Hudson Valley of New York, (i.e., not in Manhattan).
In the aggregate, the system is quieter, has more dynamics and plays louder (without sounding loud). Part of that is the room, which is probably better, sonically, than my last room.

@asp307

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Those additions to the system were done one by one over the course of the year and with several months in between each. Wasn’t planned that way...just how it worked out.  We don’t have a plan.

Completely "new" system with two pairs of speakers. And I am satisfied. I listen to different music on different speakers. Or I change the speakers under the mood :)))
Chord Mojo + Sansui B2102 Mos Vintage + Tannoy Berkley + 
T+A TB160
The first system for many years, when you do not want to sell anything :)))

My system comprises many DSPs distrubuted between two computers, one a source-plus-DSPs front end, the second the 'active crossover' for a 7-way system (pair of 3-ways with single sub). Changes are numerous partly because of this; a pair of pcie soundcards are (besides the computers) the only actual hardware before the power amps, all else being software. Thus, the biggest change was a computer upgrade.

The originals had Celeron dual-cores, but in late summer I found a sale online for refurbed HP Compaq Pro 6305s with quad-core AMD processors plus a bunch of expansion slots and decided to give them a shot. They were only $160 apiece! Apparently some big company dumped its workstations for new models and they hit the refurb market all at once. Anyway, it was a great move. The machines proved so fast compared to the originals that I was, e.g., able to extend my FIR crossover filters to a huge 64k taps/channel (over all 7 channels), way above what my old machines could handle comfortably. The sonic improvement has been very obvious and satisfying. I'm still experimenting with squeezing all I can from the new setup on both ends.

Purist Audio Dominus Rev B Ferox power cord for the integrated amp and Tchernov Cable Reference MK II RCAs for the phono stage. You never know how good your equipment is until you get current and signal transmission under control.