It is the kind of act that would make P.T Barnum’s mouth water: five handsome and talented piano-playing siblings from one fine, all-American family. If he could take Jenny Lind’s soaring voice and Victorian propriety and turn her into a household name for the next five generations, imagine what he could have done with The 5 Browns, presented jointly by the Blumenthal Performing Arts Center and Charlotte Concerts.

Of course, if P.T. Barnum had been running the show, there would have been hoards of Charlotteans at the loading dock clamoring to get a view as five gleaming Steinway grand pianos were hoisted from a big truck onto the stage of the Knight Theater, and later, throngs of ticket-buyers crowding the theater doors when the pianists sat down to play.

As it was, the 1200-seat new Knight Theater was no more than two-thirds full for The 5 Browns concert on Tuesday, February 16. Where is Barnum when you need him?

As Greg Brown, the elder of the two Brown brothers, announced from the stage, this concert was the first public performance of classical music in the new Knight. Open less than six months, the theater is a fantastic space. The entrance, next to the exotic new Bechtler Museum of Modern Art, has an energy unlike any other performance building in Charlotte. Inside, the lobby is cool and sleek, while the theater itself has a warm, relaxed feel. There is certainly nothing stuffy about it.

The hip look of the theater was a perfect match for the fashionable Browns, who played the first half of the concert dressed up – short sparkly dresses and strappy high-heels for the girls, suits for the boys – and the second half in stylish casual clothes (Greg donned Hi-Tops). But the references to the 21st century were purely superficial. This concert was 19th-century America through and through, the kind of concert that P.T. Barnum would have put together, or John Philip Sousa, or even Theodore Thomas, the great conductor who longed to be faithful to the integrity of the orchestral masterworks but knew, too, what it took to sell a ticket: variety and virtuosity.

In various combinations, The 5 Browns played 12 pieces (plus an encore) – a little Broadway (a solo piano arrangement of “My Favorite Things”), a little Hollywood (a five-piano arrangement of Star Wars themes), some finger fireworks (Prokofiev’s Toccata, Op.11), some salon pieces (Chopin’s Fantasie-Impromptu, Op. 66), and orchestral favorites recast for five Steinways (three movements from Holst’s The Planets, Gershwin’s “Rhapsody in Blue,” and a show-stealing rendition of “Danse Macabre” by Saint-Saëns). Everything was performed with grace and commitment, from memory.

The 5 Browns are all engaging performers. Each spoke at some point during the evening, and while they are well beyond the teenager stage of their early fame (they are, as Ryan, the youngest, told the audience, all married – and old enough to be so), they still present themselves as charming ingénues. To see them all at their pianos (arranged in a sort of clam-shell shape) playing in synch and entranced, is a sight to behold.

Unfortunately, the Knight Theater has no shell. When the building project threatened to exceed budget, the shell was deleted from the plans to save money. Efforts are underway to secure funding to purchase a shell, but at the moment, there was nothing to propel the Browns’ sound forward – not even piano lids, which had to be removed to fit the fancy configuration. The sound just traveled straight up.

The result wasn’t so much a lack of volume as a loss of definition, brilliance, drama. Particularly in the bass register, in works such as “Mars, The Bringer of War,” passages that should have been powerful and booming were instead thick and muddy. The upper register fared better, and in pieces like “Neptune, The Mystic” and a two-piano “Grande Tarantelle,” by Louis Moreau Gottschalk, the quick and delicate finger work shimmered.

But the lack of a shell did not seem to dampen the musicians’ verve or the audience’s enthusiasm, and as the siblings signed off with the Alfred Hitchcock Presents theme (Gounod’s “Funeral March of a Marionette”), the crowd cheered. Barnum would have been pleased.