End of the line products.

I'm interested in those products that you've found "End of the Line", meaning no reason to keep searching, you've been satisfied with this product for 5 years, and see no reason to keep spending up the equipment ladder. For me, Essence Amethyst speakers, and Essence pre amp and amp now date to the 1990s.
My Deja Vu preamp and amp and Yamamoto Dac would all qualify. I’ve had my speakers also for 9+ years original JMlabs Micro-Utopias, but can’t say I won’t replace those eventually.
FWIW, my (original) Sonus Faber Electa Amator speakers, and my Stax headphones (various models, currently 009s). I have had the speakers since new, about 25 years. The Stax really are the "End of the Line" as they are the current top of the Stax line. I will never sell either the speakers or the headphones.
My Chalice Audio 'Grail' SET monoblock amps...."maybe the best tube amps made".....
Hyperion Sound HPS-938 speakers.  There are a lot of better speakers, I'm sure, but Hyperions midrange is to die for.  They are also warm sounding with perfectly integrated tweeter.  Unfortunately company went out of business for the lack of marketing and dealer base.  Good product is only part of success.
Spectral. MIT.Sound Application.