Astute followers of Jacksonville’s red hot jazz scene are surely familiar with DeAndre Lettsome. A founding member of Jax-based purveyors of New-Orleans-style jazz, Let’s Ride Brass Band, the 26-year-old alto saxophonist is an in-demand player. And, as evidenced by the new nine-song collection Impetus (Lettsome’s first solo release on Bold City Music Productions), he’s also a formidable composer and topnotch …