Although Omar Sosa has excelled in group settings, the Cuban pianist has demonstrated that he is also quite comfortable playing unaccompanied, which is what he does on Calma. Sosa has no accompaniment at all on Calma, a 2009 recording that combines post-bop with elements of world music and Euro-classical music. He not only plays the acoustic piano here; but is also heard on electric keyboards and using some sampling and electronics. And the very fact that Sosa doesn't adhere to an all-acoustic-all-the-time policy on this 51-minute CD will no doubt scare jazz purists away. Regardless, Sosa's acoustic piano is the dominant instrument, and 95-percent of the time, Calma sounds played rather than programmed. In both Spanish and Italian, the word "calma" means "calm," which is exactly how Sosa sounds on this album; his playing is calm and relaxed, and a contemplative mood prevails on originals such as "Innocence," "Esperanza," "Walking Together," and "Aguas." That is not to say that Calma is one-dimensional. Different world music influences assert themselves on different pieces, and during the course of the album, Sosa incorporates everything from Afro-Cuban music to Indian, Middle Eastern/Arabic, Asian, and North African music. Plus, there is the Euro-classical influence: "Dance of Reflection," for example, hints at Erik Satie (who died in 1925 but continues to influence both classical and jazz musicians after all these years). So even though Sosa maintains a certain mood on Calma, there is also a fair amount of variety. Again, Calma doesn't cater to jazz purists, and the rigid dogmatists and musical ideologues who think that Chick Corea, George Duke, and Herbie Hancock sold their souls to Beelzebub when they started playing electric keyboards, will want to avoid this album. But for those who realize that non-acoustic instruments do, in fact, have a place in jazz, Calma is yet another absorbing effort from Sosa.