Best USA city to audition a system.

North Dakota. 

I one is willing and able to spend five (six?) figures on an audio system, an in person audition is obviously desirable.

Really? Explain it to me. Because I have the distinct impression what is desirable is to find the best components. No dealer anywhere ever had the best of everything. It just don’t work that way. I think what you are looking for is one that will do the best job of hand holding emotional reinforcement and making you feel you got a good deal while putting 60k into his pocket, 40k into your living room. Because the way you are going that is exactly what will happen.

If that sounds harsh, well rest assured the best dealers are so good at it you really will feel you got a good deal, even as he drives away in the Ferrari you just paid for.

@kjohn1234 

I recommend you swing by Brighten Michigan, Classic Audio Loudspeakers & Atma-Sphere resides close to there.... It's a chunk of change not to consider different options.

http://classicaudioloudspeakers.com/cgi-bin/index.pl?fs=1&init=1

The T1.5 Reference is what I recommend you give a listen too.

http://www.atma-sphere.com/en/index.html

Try asking the google. Occasionally it’s good for something. However you may want to create a list of manufacturers you are interested in,then look for dealers. You very well may have to visit multiple dealers. Enjoy the hunt. 

Chicago has many dealers but you will do a lot of driving.