Trending on Billboard There are a few official electronic music museums in the world, but one of the most expansive collections of dance culture paraphernalia must be in Pasquale Rotella ‘s office. Explore See latest videos, charts and news The sprawling space within the chic Insomniac Events office in Calabasas, Calif. is a trove of art books and vinyl, stacks of rave flyers, clothing, a whole area that appears to be just toys. “Look at this,” Rotella tells me, excitedly holding out a Techno Viking action figure still in its packaging. He’s got framed pages of ’90s scene bible  URB Magazine . A collection of posters leaning against the wall ready to hang include a vintage ad for rave wear brand Clobber. There’s a shelf of gifts fans have given him over the years. He shows me a vinyl record on which a woman affixed a long letter, written in childlike bubble handwriting, about how Insomniac shows changed her life.…