Since its opening in 1994, Smalls progressed rapidly from a low cover, live workshop for “unknown” players to becoming the creative center of the Manhattan’s downtown jazz jammin’ scene. Jazz Underground-Live At Smalls is the first “official” recording of what’s been going on there. A showcase for six strong new bands (Omar Avital group, Charles Owens Quartet, Zaid Nasser Quartet, Across 7th Street, Frank Hewitt Sextet, Jason Lindner Big Band), the album is brimming over with the elixir of future promises. From the plaintive sublimity of “Everything Happens To Me” (Zaid Nasser Quartet) to the 13-piece Jason Lindner Big Band’s Monk-esque swingset “Phat,” the music is full of energy, infused with a communal delight in pure swing. Sign ’em up.