When and what was your last significant equipment upgrade?

ProAc Studio 148 mini towers in mahogany in Jan 2016. Check my system page for photos and details. Great speakers with amazing clarity in mids and highs plus the downward firing port helps with flexible placement and great bass response to 20hz. 

 jond, its brown, doesnt work on holidays or weekends and comes pre broken (in)

I just completed a reference DHT  Triode preamplifier ,
and a F6 Pass labs 1st watt amplifier  this builder is excellent with several degrees in electrical engineering
my pre has the 26, and 101 D  tubes.

https://simplepleasuretubeamps.wordpress.com/

A used Matrix M Stage HPA-1 headphone amp/preamp (2012/v.2). It cost little & really impressed me sonically, bettering my Burson Soloist in certain ways. I'm upgrading it with w/OPA627AP opamps & using as my day-to-day preamp.

Parasound JC3+ phono preamp -- what a fine piece of gear and a real value.