Synth pop wasn't intended to have a soul. Pioneered by German techno wizards Kraftwerk in the '70s, electronic pop music became a haven for chilly detachment. Without the hollow baritone of vocalist David Gahan (born David Callcott), there wouldn't be much fire in the synthetic grooves of Depeche Mode. When Gahan joined Depeche Mode in 1980, he was the group's missing puzzle piece, a charismatic, stylish singer. In the beginning, Gahan sang in an icy yet upbeat fashion, milking the hooks from early Depeche Mode hits such as "Just Can't Get Enough" and "Dreaming of Me" with boy...