Rarely does an album write its own review so succinctly. When “It’s Been a Delight” closes the debut of this Chicago quintet, it encapsulates the fizzy intoxication of the whole aural experience. Though the band has long been beloved in its hometown clubs, its members might be better recognized elsewhere from other configurations: Kelly Hogan and Nora O’Connor as perpetually indemand vocalists (most recently on tour with the Decemb-erists), while guitarist-keyboardist Scott Ligon and bassist Casey McDonough are latter-day members of NRBQ. Alex Hall tends to stick closer to home, as one of Chicago’s busiest drummers. With an encyclopedic musical command, a Flat Five performance is likely to range from Charlie Rich to Sly Stone to archival obscurities from all over the musical map. On It’s a World of Love and Hope (out October 14 on Bloodshot), the band has narrowed its focus to material by Scott’s older brother Chris Ligon, who is sort of the songwriting equivalent of an “outsider artist.” Though never nostalgic, the harmony-laden, crisply-arranged results recall the era when popular music was making the switch from AM to FM, and singles to albums. Imagine the Fifth Dimension scoring Twin Peaks. Or a version of “California Girls” that switches genders and coasts, on the album-opening “Florida.” Or just savor “This Is Your Night” and “Almond Grove,” stunning beyond comparison. For a band brimming with personality and musical chops, individuality takes a back seat to interplay that serves and enhances the material. The Flat Five are a song’s best friend.