What is the most challenging music to play on a stereo?

If you really wanted to test the ability of a stereo, what type of music would you choose?



thanks so much for that explanation.  Totally makes sense and gives me more appreciation to listening for details with piano playback in my system.  I also have to add that playing at the proper volume would get you closer to realism, just don’t overload the room.  This discussion is quite interesting with everyone’s feedback and vast knowledge and experience. 

Pipe organ. When I bring such recordings to demo audio most won't even play it. Others look like scared rabbits when asked.