John Fedchock and onetime Chicagoan Paul McKee first met in 1984, when they were two-thirds of the trombone section in the Woody Herman Orchestra. Herman led a galvanic big band that never stopped evolving, thanks to his use of younger musicians and the new arrangements he encouraged them to write. Fedchock was the star arranger for that last edition of the Herman band, and not long after Herman's death in '87 he assembled a juggernaut orchestra of his own, the New York Big Band; its brand-new Up & Running (Reservoir) shimmers with his vibrant charts. But Herman's legacy is audible in McKee's writing and arranging too, as demonstrated on his 1999 disc Gallery (for which Fedchock contributed liner notes). Such facility with work on the larger canvas helps these two even when they're painting miniatures--as in this weekend's shows, where they'll colead a quintet. That's partly because playing on a front line comprising two of the same instrument demands an arranger's attention to detail, and partly because Fedchock and McKee think like writers even when improvising on their horns: both display an unusual appreciation for texture, focus, and organization in pretty much every solo. Elegant pianist Jeremy Kahn heads the rhythm section. See also Saturday. a 9 PM, Green Mill, 4802 N. Broadway, 773-878-5552, $12.