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

Metallica’s Hardwired... to Self-Destruct album is like a tester for any system ability, you can check almost everything including very important index of dynamic range, however this Album-tester is not for tube based amps, very few of them could handle that kind of dynamic. 

The Chariots of Fire theme by Vangelis is one I play for others. Love it !

Happy listening 

Definitely vocals - trying to make Tiny Tim's voice sound better is definitely a step in the right direction

Your system and the music you play on it can be the very best money can buy and still fall very short if your room acoustics suck. Over the many years that I spent chasing the best sound the one and only real lesson I learned was to get your listening room properly tuned to your ears and the system playing the music you enjoy. Every room is different and a simple change of your listening position or speaker placement can make a huge difference. Softening the room so you eliminate reflective noise is probably the most beneficial change you could make. Most of us are not able to dedicate that much space and design engineering to our rooms yet we spend massive amounts of money on our systems. You can put a Hemi engine in a VW but that does not make it any better. Get your room right. 

@gandmjl 

Over the many years that I spent chasing the best sound the one and only real lesson I learned was to get your listening room properly tuned to your ears and the system playing the music you enjoy.

+1