Formula, Vol.

1, the debut offering by Anthony "Romeo" Santos, former lead vocalist for Aventura, was preceded by two hit singles.

First was the easy summertime groove of "You," followed by "Promise," a shimmering duet with Usher.

Both tracks hit the top spot on Billboard's Hot Latin Songs and Tropical Songs charts.

On this 15-track full-length set, Santos offers proof that the singles were merely teasers.

Kept mainly to slow to midtempo ballads -- all of which he wrote or co-wrote -- Santos and his slippery tenor cross bachata, nuevo flamenco, and merengue, melded with just enough contemporary R&B, to create an intoxicating brew.

Other standouts include "Soberbio," "La Bella y la Bestia," and "All Aboard," in collaboration with Lil Wayne.