Back in the days when I was learning piano, I often hear my teacher play the song once or twice in the beginning, rely on your memory and your reading skills and try to play the song. I was one of the luckier guys when I was in University and can use the record (vinyl) collection in the music library to hear the music while reading the score.
Last night my son told me that we were tasked to pick a new song (list C) for him to play and the recommended composer is Rachmaninov. So I opened up imslp and search what they have. We then look for the corresponding pieces on youtube and have these great pianists playing for us. We picked prelude op 23 no 5 - something I haven't played myself.