This story is a sequel to Aria's Aria
After one of them listens to a new album and looks at its cover, the Rainbooms are shocked to see that the singer may be one of the Dazzlings. Meanwhile Aria Blaze is a relatively new rising star, complete with a rivalry of sorts.
Takes place between Rainbow Rocks and Friendship Games.
(Note: Despite the Mane 6 Humane 7 tag, there is no Twilight Sparkle in this story. I would've gone with a Humane 5 tag if we had one. There's not enough space to tag them individually/tagging them individually would overstate their role.)