Singer Petra van Nuis (pronounced Pay-tra van Nouse) and guitarist Andy Brown could legitimately be called Chicago’s First Couple of Jazz. The married pair is a fixture on Chicago’s vibrant jazz scene, frequently performing as a duo, but also working alone and together with many other musicians in a great variety of ensembles. Their focus is on swing-era music, that golden age of jazz between the two World Wars, which produced some of the most famous players and composers and also gave us many of the best-loved tunes in the Great American Songbook. Besides those standards, van Nuis and Brown have an enormous repertoire of more obscure songs, but ones with equally clever, literate lyrics, lovely elegant melodies, and rich, sumptuous harmonies.

Van Nuis’s voice and stage presence perfectly project and convey these songs. Her vocal quality stays seamlessly the same throughout her range, and her straight-tone style, with no hint of vibrato, is highly expressive. Her naturally cool, hip, yet engaging demeanor provides the perfect foil for these suave and sophisticated songs, and Brown is her ideal complement. While van Nuis maintains almost constant eye contact with the audience, Brown is focused on his fret board and traverses its length and breadth with ever-inventive chords, arpeggios, and solo lines. He’s adept at finger-style, cover-all-the-bases accompaniment, simultaneously conjuring moving bass lines and piano-like chords and melodies from his electric hollow-body Gibson. He also creates irresistibly driving flat-picked rhythms, and he solos with authority. Neither is into pyrotechnics, choosing nuance over flash but with an intensity that generates plenty of excitement.

It’s not often that a concert is worth attending as much for the sidemen as for the main act. First of all, the term “sidemen” is a major misnomer here. “Dream Team Rhythm Section” is more fitting. Pianist Jim Dapogny, bassist Paul Keller, and drummer Pete Siers are each highly successful local bandleaders, players, and educators, and have all garnered numerous honors and many longtime local and far-flung fans. With players of this caliber, the typical distinctions between front men (and women) and sidemen disappear.

All five are steeped in this material and know its conventions so thoroughly that they can create spontaneous arrangements on stage that simultaneously sound like they are written out note for note as well as improvised off the cuff. Van Nuis leads like a seasoned air traffic controller, directing who will take off on the next solo, who will fly tandem with whom, and when and how they’ll land. When they played together for the first time at the Kerrytown Concert House last year, “it worked out very well,” says Dapogny. No argument there.

Van Nuis, Brown, Dapogny, Keller, and Siers return to the Kerrytown Concert House on Friday, September 9.