Contains Rachmaninoff´s most famous piano piece, the Prelude in C-sharp minor. This paired with the ten pieces from opus 23 provide the advanced pianist a newly-engraved and researched edition of the first half of the composer´s output of piano preludes. Audio is accessed online using the unique code inside the book and can be streamed or downloaded. The audio files include PLAYBACK+, a multi-functional audio player that allows you to slow down audio without changing pitch, set loop points, change keys, and pan left or right.