What was the first system you heard that made you think the high end made sense


I am sure I cannot be the only person here who can recall the day, and indeed the very system that made them think 'oooohhhhh yesssss - I get it - I understand - and I absolutely love it!'

In my case I attended a HiFi Show in Heathrow at the Renaissance Hotel. It was the GT Audio room hosted by Graham Tricker. The parts comprised:

DPS turntable- Schroeder arm - jan allaerts cartridge
Tron Pre-amp
Avante Garde Uno's

In all honesty I still remember the day now. It was so musical and had the ability to connect me to the music. When I went for a full demo at Grahams home I came to understand the magic of horns, valves and imaging. 

lohanimal
The first time I ever heard an SET amp was at a SET Symposium in Philadelphia put on by Stereophile magazine.  A whose who of audio people were there and that day I got to hear about 10 different SET amps using 845s, 211s, 300Bs and 2A3s all played thru a CAT SL1 preamp and Sony SACD player.  To me, the best sounding amp was the lowest powered and least expensive as well, Fi 2A3 monoblocks.  That's where I took my username because I think SETs sound best.
Big Krell amplifiers and Martin Logan Statement speakers. I can't recall the other components.
1978 Klipsch setup of some sort coincidentally at G&T (Groove and Tube) dealer in Lancaster PA playing Fleetwood Mac Fleetwood Mac album.    They also had a Magnepan Tympani setup that also impressed me.  I never heard the term hi end until many years later possibly first on this very site. 
Panasonic boombox. I thought it sounded so bad that to get a good sound I would have to have a high-end set-up.
ESS Transtatic speakers driven by an ARC SP-2C pre-amp and Dual 50 power amp, the source a Sony turntable with a Decca Blue cartridge mounted on the Decca International arm, in 1971. Pure lust. I heard the original Infinity Servo-Statics shortly thereafter, and starting saving. By the time I had the $ the following year, the Magneplanar Tympani-I's had made it to the West Coast, and I got myself my first serious system.