The perfect speaker system is indistinguishable from having a live band in the room with you (when blindfolded).

Can today's audio systems do that? How much money do I have to spend to get there?

The sound system isn't the limiting factor there, the recording itself is. If the input wasn't recorded with that in mind, no amount of money wasted on the outputting system can fix that.

Usually you only get some specially-crafted demo files that are capable of fooling you.

I am quite sure live band will definitely sound worse than most sound systems.

My experience is I hanged out with one band in a garage where they were practicing and I attended couple live music shows in pubs.

Main upside of those live music shows is that they are not "perfect" like playing a record and each one of the gigs will be off here or there, tempo somewhere will be off or a tune will be off - or you are just having enough beers you don't care pick your way :)

I've been in demo rooms that priced in about $100-300k (~2015 dollars), and those sound remarkably close. Not all sound/bands can be reproduced, and it really depends on the recording. Could you do it for less, also? Probably. But it was pretty fun to hear the highest end.