Most satisfying system change in 2017?

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.

Finally finding and buying the Krell B&W Bass Alignment Filters  pair (balanced) for my B&W Matrix 800s..  Now its time to relax and really hear what these baby can do !!!! 

Not much to report other than a 1.5 meter of the new MIT Heritage series interconnect, an EVO 2 between my preamp and amp.  The best MIT IC I have had, equal to my 350 SG EVO. 

The marketing machine at MIT is truely delivering some trickle down from it's uber priced reference line.