I’m gob smacked. What were you’re aha moments?

(great thread) I'll keep it in the last 5 yrs, since all my really big 2-channel moments were 35+ yrs ago.

I have a pretty robust desktop system. For years I got along with less than audiophile 2.1 speakers/sub. Pretty good, but not as good as possible. Last year I bit the bullet and bought a pair of ATC SCM 12 Pro's. DAMN! Not only are they the best 2-ways I ever heard, but they manage an extreme tightrope-walk of great accuracy w/o sounding edgy/tiresome. Great monitors.

The other big moment was finally getting a non-oversampling (NOS) multibit DAC and replacing my pretty good delta-sigma DAC on the desktop. For the first time in all these years listening to digital, I'm able to totally relax and not hear music files as "digital," just as music. That's kind of priceless...

Hmmmm-- Audio research Ref 6 - wow- Spatial Audio Speakers M3 Triodes--wow-Ref Cd9--Those were the wow times

This past year I replaced my entire system a component at a time. Consequently, many a smack. What made the largest change for the better was my recent XD upgrade to the Krell 575 Solo. Amazing. 

1969----There I was, a High School Senior listening to KLH-9's.I knew I had to get a pair.
1973----At a yard sale I picked up a Magnavox 175 chassis for $5.
When I realized that it was better than my Marantz 8b I started building.

Upgrading to Aragon Iridium monoblocks and then playing Yello - Flag vinyl through them... mind blowing