I'm interested in hearing what "the best" systems sound like, where to go?

If your satisfied with your system, don't tempt the audio gods, just enjoy your system for the effort already invested. Nothing wrong with hearing different systems but we as a group tend to lose sight of the system at hand, kind of like having a beautiful, great girl friend, dropping her for another just to find out you can't live with the new one and wish you had the old one back. Just sayin

Your best bet is still an audio show. I used to travel to neighboring states to hear systems at dealers. I even looked for audio shops when on trips around the world. 

There is as much variety in audio salons as there are in shows. You will hear some of the best at shows. Take the room into consideration and enjoy the gear as presented. 

Beware of claims of "the best". Think of performance not as a peak, but as a range of ridges of varying heights. There are MANY superb components, speakers, cables, etc. There are MANY systems that are world class. There are usually at least two or three memorable, stunning rigs at shows. 

You don’t say where you live. In my area (Dayton, OH) there are still audiophile 2 channel brick and mortar dealers where company reps will have shows occasionally and permit critical listening to some fantastic medium expensive and ridiculous, out of reach expensive systems.

But I agree with you that listening to the out of reach systems is instructive. I got to listen to a huge ballroom sized system of the biggest, most expensive Focal Utopia loudspeakers driven by a Boulder solid state amplifier the size of a dishwasher. Very amazing, fun experience for all. I was not an opera fan before, but someday I could be one thanks to demos like that. And just a re-listen of Fleetwood Mac’s “Dreams” album on a great turntable over this system was a real revelation over songs that I thought I was completely familiar with.

I would encourage you you to go to whatever big city is near you and make a visit at some different dealers and familiarize yourself with some different product lines. I know for me, I assembled my audio system backwards from the speakers, which in my case are Thiel CS3.6. Notorious power hunger made spec’ing my Bryston 4Bsst2 amplifier a choice that I felt pretty great about. You might have different priorities for amplification or speaker attributes.

Listening to those uber-expensive demo systems educated me on what compressed dynamics weren’t. It is the definition of what uncompressed dynamics are! I suffered through my favorite music on CD’s played over a Sony D5 Discman through a harsh sounding NAD 2200 amp for 30 years! I knew my system was fatiguing and finally set out on a discovery quest on ways to dig deeper into my favorite well recorded music that I knew damn well had many, many added layers of detail to them that my equipment at the time could not un-ravel.

For my money, I feel like Bryston components are a fantastic old-fashioned value. The current cubed series amps are worthy of an audition. It would be worth your while to search for the nearest dealer near your zip code and make a day trip out of it. I haven’t listened to the Bryston 4Bsst3 amp yet - if I could convince my local dealer to get one in stock and set up a proper demo, I would most likely purchase the amp on the spot if its performance is to the 97th% of perfection that I suspect it is living at.

That gentle readers is the $64,000 question. Having had the misfortune to live in Dayton, I would be inclined to eliminate Dayton from consideration. 🤗