It was worth the wait. Fluid Motion — a quintet headed by composer/trombonist David Manson — released a debut CD last year, one of the best jazz albums of '03. When they finally debuted on stage at the Palladium, the ensemble fittingly turned in the best jazz show of the year. Fluid Motion has quite a pedigree. At the forefront is legendary saxophonist Sam Rivers, still frisky and vibrant at 79. The group also includes his long-time rhythm section — drummer Anthony Cole (who played brilliantly on this gig despite having only a bass and snare drum, hi-hat and ride cymbal) and muscular bassist Doug Mathews. Add to this a revelation: trumpeter Jonathan Powell, 21, a former Largo resident who now calls NYC home. His brassy tone, hard-charging swing and barrages of notes brought a youthful verve to the proceedings. They were joined by Manson, who had composed the set of angular tunes that walked the line between post-bop and avant-garde. The gig's only amplification was a small bass amp. The three horn players stood behind music stands and playfully executed the tricky arrangements and soloed with gusto. The crowd pushed 200; they were enthusiastic in their applause. Who'd believe it: a world-class acoustic jazz show in Tampa Bay.