Solving Music: chelmico - Easy Breezy
You'll notice that there's no Across Lite or PDF links for this puzzle. You'll also notice that the grid in the applet is absolutely terrifying to look at. This puzzle is meant to be solved in the applet, so I've decided to leave out the links this time.
It's pretty difficult to talk about this puzzle without spoiling the revealer/theme, so I'm gonna openly talk puzzle spoilers (and explain the theme if you're out of the loop) below this break: