I have heard a number of really expensive systems over the years. One thing I have found is that seldom will you hear the potential at conferences or small dealerships. They get stuck with horrible compromised rooms with no time to fiddle.
There are some places that have a listening room and expertise to make their components sound good: Overture in Delaware comes to mind. I flew out there to audition some equipment… they did a great job in setup.
The best system I have heard was about $750K. It was Wilson based. It had a permanent room set up (large). I was just blown away. The best system I have heard… however, I also said, “I don’t want that”. Ok, if I could have two systems… sure.
But, there are a lot of “kinds” of systems. Flashy… Liberace like, modest more balanced, really musical… sounds like the real thing. so, it also depends really strongly on what you want.
If you are careful and meticulous you can put together a great sounding system on a modest budget. But assuming the same care and effort a $50K system will sound much better than a $25K system… and a $100K system will sound much better than a $50K system.
I own a $150K system… after pursuing high end audio for fifty years. In that time my understanding of what constitutes a great sounding system has evolved considerably… as well as my systems costing more. I have heard many system in the same price range or higher, I own the best sounding system I have ever heard.
My values are strongly influenced by spending the last 25 years listening to acoustic instruments as much as possible as well as attending hundreds of symphony performances.
If I could afford a $300K system, I am sure I could put together a better sounding system. But in the mean time I love the system I have. It is not a megabuck system in the high end audio world but is carefully tailored to my tastes. You can see my systems under my usedID.