Your Forever Pieces? What and Why?

Pretty sure a number of members have some equipment they have owned forever or intend to where feasible.
Curious as to what, how long so far and why?
My oldest factory piece, still in use(since 1980): a Magnepan Unitrac I, tonearm. The only change made to that, was creating an adapter, to allow upgrading it’s interconnect cable. Now mated with a Soundsmith cartridge, a golden(maybe platinum) combo. Also, circa 1980, one of my customers requested an actively crossed over pair of 10" driver, folded, 8’ transmission line woofers, to mate with his Acoustat Model IIIs. After building his and hearing the results(with a modded Hafler DH-500, driving them), I built a pair for myself. They’ve been providing fast, dynamic/impactful, tuneful bottom end for me, ever since. A few years back, I swapped out their Milos Nestorovic sourced, 10" drivers, for Seas L26RO4Ys.
After 40+ years endlessly buying and then selling my audio equipment, I’ve streamlined the whole shebang down to a Simaudio 700i Integrated amp, CD player and Focal Soprano No 2 Speakers. 

Only future upgrades I’d consider would be in the source.
Maybe a Hi-End MQA server or whatever sounds better down the road with my current equipment ?

Can’t afford now want the hassle of a turntable/tonearm/MC cart/preamp anymore. 
I’m really happy with the system. 
Just replaced (but still own) Dalquist DQ-20’s bought around 1989. Wonderful  sounding speakers used and enjoyed for almost 30 years.
Also, Conrad-Johnson PV11 preamp from ‘90s. Still using. Just had Teflon caps installed.