Bristol's soundsystem culture taught Massive Attack to mix dub, hip-hop and post-punk, and that same open-minded approach continues to guide the trip-hop pioneers: They've worked with reggae greats Horace Andy and Mad Professor, and they captured Sinead O'Connor at her most ethereal on the spine-tingling "What Your Soul Sings". Their style may change, but their moody depths are unparalleled.