Diana Krall paid tribute to her father on Glad Rag Doll, the 2012 album sourced from his collection of 78-rpm records, and, in a sense, its 2015 successor Wallflower is a companion record of sorts, finding the singer revisiting songs from her childhood. Like many kids of the 20th century, she grew up listening to the radio, which meant she was weaned on the soft rock superhits of the '70s -- songs that earned sniffy condescension at the time but nevertheless have turned into modern standards due to their continual presence in pop culture (and arguably were treated that way at the time, seeing cover after cover by middlebrow pop singers). Krall does not limit herself to the songbook of Gilbert O'Sullivan, Jim Croce, the Carpenters, Elton John, and the Eagles, choosing to expand her definition of soft rock to include a previously unrecorded Paul McCartney song called "If I Take You Home Tonight" (a leftover from his standards album Kisses on the Bottom), Bob Dylan's "Wallflower," Randy Newman's "Feels Like Home," and Neil Finn's "Don't Dream It's Over," a song from 1986 that has been covered frequently in the three decades since. "Don't Dream It's Over" slides into this collection easily, as it's as malleable and timeless as "California Dreamin'," "Superstar," "Sorry Seems to Be the Hardest Word," or "Operator (That's Not the Way It Feels)," songs that are identified with specific artists but are often covered successfully. Krall's renditions rank among those successes because she's understated, never fussing with the melodies but allowing her arrangements to slink by in a deliberate blend of sparseness and sophistication. It's an aesthetic that helps transform the Eagles' "I Can't Tell You Why" and 10cc's "I'm Not in Love," singles that are as successful as much for their production as their song, into elegant torch songs, yet it doesn't do much for Newman's pedestrian "Feels Like Home," nor does it lend itself to the loping country of "Wallflower," which may provide the name for this album but feels like an uninvited guest among these majestically melodic middle-of-the-road standards. These stumbles are slight and, tellingly, they put into context Krall's achievement with Wallflower: by singing these songs as sweet and straight as the dusty old standards on Glad Rag Doll or the bossa nova on 2009's Quiet Nights, she demonstrates how enduring these once-dismissed soft rock tunes really are.