Classical music rewards close listening, but orchestral pieces can be overwhelming to those who haven't trained themselves to listen closely. This is a good set of recordings to start with, as there are only a handful of performers, each with a distinctive sound.

Digression: once one has learned the pieces, this can be a good audio assessment tool. Some speakers over-amplify specific sounds. Some amps muddy certain frequencies or complex sounds. A string quartet performing similar melodies is a great way to notice this.

This specific album was the first that really opened my eyes to audio quality differences. If all four instruments are playing, I should be able to hear them. If all I can hear is the viola, there's something wrong with the system. Or, if I can suddenly hear all four where I couldn't before... These are significant differences, not minor ones.

From there, it was learning finer details. The first time I could hear the attack, sustain, and release of a note on a stringed instrument. Changing equipment and suddenly getting what "soundstage" meant. Etc.

This album also kept me honest when diving into the potentially incredibly expensive and super opinionated audiophile world. How does this compare to my personal system? Am I noticing anything I've not noticed before? Is anything missing? Do the answers to these questions justify spending money? Surprisingly, the answer most of the time to the last question was no.