What is the best sound system you ever heard?

@orpheus10, but even after a hundred years or so that's one of the hallmarks, a key reference point of all audio (domestic, film, broadcast etc), isn't it?

Of course you can't reproduce the  acoustics of the Albert Hall in your car but you could still get an idea, couldn't you?

One sound system comes immediately to my mind and is open to the public (with some advanced planning).  Synergistic Research's listening room in Santa Anna, California. Every aspect of what can affect sound has been considered and addressed. Also, it is one of the few rooms where Digital, Vinyl, and Tape are all optimized.

For me, it is a great learning experience to use this listening room as a benchmark for my systems.
David Pritchard

Not an electronic system, but the best sound I've ever heard was the Vienna Philharmonic Orchestra playing in the Musikverein  in Vienna.