Due to the steady stream of dance/hip-hop/techno reissues and compilations, it's inevitable that a good deal of material is going to overlap. Tommy Boy's The Perfect Beats, a four-volume series of classic electro tracks from the watershed years of 1980 to '85, features some songs that also appear on the confusingly titled Greatest Beats, the label's simultaneously issued rap set. Making matters more confusing is that there's just as much overlap with Rhino's four-volume electric-funk series, another fine collection released just a couple of years ago. But the tracks that get repeated the most, such as Afrika Bambaataa's "Planet Rock," are so monumental that any collection missing them also misses the point. "Planet Rock," a track fronted by a black man (Bambaataa), recorded by a white man (Arthur Baker), and inspired by two Kraftwerk songs ("Trans Europe Express" and "Numbers"), is just the kind of shot-heard-'round-the-world crossover that marked the transition between disco and rap. The same could be said of Shannon's "Let The Music Play," a Latin hip-hop hybrid that blew up dance floors and sent dozens of producers back to the studio. The Perfect Beats features 58 such songs from artists both obscure (Peech Boys, represented with "Don't Make Me Wait," and Liquid Liquid, whose "Cavern" was remade as "White Lines") and famous (Yaz, New Order, Level 42). Modern dance music owes so much to such innovators as Baker, Bambaataa, Kraftwerk, and John Robie—producers and musicians who saw the future in computers, MIDI, and other electronic music-making tools—that these perfect beats still cast a long shadow over bedroom DJs and vinyl-spinning savants everywhere.