Unfortunately that's not even the hardest puzzle in the game. Much later there's a water sample puzzle and that one is freaking almost impossible to do without a walk through for me and I'm usually pretty good with puzzles of RE games.
actually the first time I played this game, the music box puzzle threw me off because I didn't understand the IDEA behind it- then it hit me that it wants me to choose the correct sequence of notes to complete the song.
I think that music box was a waste of time to complete but overall: water sample > music box puzzle in terms of annoyance. The music box puzzle might take a little longer. I don't wanna have to remember stuff just give me the solution! :>