The most expensive system I can remember hearing was a Naim Audio based system that in today’s inflation adjusted dollars would be worth somewhere in the area of $150,000.
I’ve always thought it ironic that most of the audio enthusiasts who can afford the most expensive gear tend to be older people whose hearing is not as acute as it was when they were younger. As such I have wondered about the wisdom, strictly from a common sense standpoint, of investing such a princely sum of money on a state of the art audio system, when the final component in the audio chain (namely one’s own ears) is not equal to the rest of the system.
Of course this is just my subjective opinion and should be taken with a grain of salt.