I think doing the whole audio file at once is a worse direction than doing melody, vocals, chords, lyrics, beats as separate elements. I've focused on melody and I'm happy with my results: https://www.youtube.com/playlist?list=PLoCzMRqh5SkFPG0-RIAR8jYRaICWubUdx. I'm about to run a Mechanical Turk study to compare their quality to fully human hit melodies.