José Nieves and Kenny Vázquez, aka R.K.M. (Rakim) and Ken-Y, follow the familiar reggaeton fast-rhyming rapper and silky suave singer formula, but still stand as a force to be reckoned with in two years, they have become one of the genre’s most prominent duos. Natives to Puerto Rico, their 2006 debut Masterpiece, which featured the mega-hit “Down,” won over fans internationally. The pair now capitalizes on (“commemorates” seems too strong a word) that album’s one-year anniversary with this two-disc set—a reggaeton lover’s dream that includes four previously unreleased songs and remixes, with guest shots from seasoned giants Daddy Yankee, Nicky Jam, Héctor “El Father,” and Pitbull. Masterpiece is surprisingly diverse, with the acoustic-based “Dame Lo Que Quiero,” the reggae-infused “Amigo,” and the slow R&B jam “Dime” countering the continually thumping dembow beat and harder-hitting tracks like “Hey Chula.” Topped off with bonus DVD footage of live performances, studio sessions and videos, this set—questionably premature as it may be—is a nice treat for the fans.