Samurai Jack - Season 3 Episode 2 -

In his travels Jack comes to a tavern and a crying tavern owner. Then shadowy figures attack but Jack discovers they are teenagers, the "Children of Aku", under a magical musical spell. Knocking one out and following them in disguise, jack finds their rave and a sinister DJ playing the music. The DJ spots Jack and a fight ensues. Jack takes the fight directly to the DJ who is his near-equal. When Jack gets the upper hand the DJ dons a speaker-battlesuit but Jack regains his lost sword at the last minute and triumphs, freeing the children.