Start a music channel.
Once you unlock the perk to be able to compose your own music, you'll end up with new ratings. The higher the rating, the better the score for subscriber output.
The easiest is Metal, on the sliders put 100% Melody and 20% Rhythm.
The other genres are as follows.
Rock : 50% M, 30% R
Pop: 10% M, 50% R
Punk: 90% M, 10% R
Hip Hop: 60% M, 80% R
Classical: 40% M, 90% R
Jazz: 50% M, 60%, R
Blues: 70% M, 60% R
Dance: 30% M, 30% R
Elctro: 40% M, 70% R
Regae: 80% M, 90% R
The sliders have to be dead accurate, which is anoying, this makes the Metal song the easiest to gain this trophy. The most annoying one is actually Hip Hop, it seems to be glitched, and often comes out as 4stars.