The enigmatic producer channels candied melodies and incandescent synths on his full-length debut. In “Know Me,” he uncorks a psychedelic sugar rush from a heavyweight trap beat, while “Summer” is a cornucopia of flashing keyboards and fizzing climaxes. Even on the darker “Bounce,” an irrepressible enthusiasm is the driving force in Marshmello’s style. “Want U 2” fuses J-Pop’s giddiness and future bass’s fervor in a magnificent overload of hyperactive cuteness. By the time Omar Linx shows up to deliver the rap that grounds “Keep It Mellow,” you’re so soaked in techno-pop stimulation that a human voice seems downright exotic.