The energy slider definitely has to do with the “Music Energy”. Combining it with the tagline “Remix everything” it gives me 3 ideas.
A) Add an extra beat to any song, adjusting the speed of it to fit with the song.
B) Bass boost slider, similar to the skullcandy crushers
C) There is a record button we dont know about yet that lets you record parts of songs and remix them into the current playing song.
Though i think the bass boost slider is more likely due to being way more fun to play with and works best across all music, the extra beat feature does sound a little fun and something new. The remix option sounds even less likely but would be the most advanced feature it could bring.