* Soul to soul: Lead vocalist Cissy Houston is mother to Whitney. The group backed Aretha Franklin, Van Morrison and Elvis Presley, among others, and influenced Luther Vandross and later harmonic outfits such as the Emotions.

* The lowdown: To hear Cissy Houston do a cover is to forget everything you know about the original tune. She deconstructs a song, lyric by lyric, then rebuilds it to entirely new emotional effect. Her “Alfie” is an impassioned meditation on faith. “Unchained Melody” is a heartbreaking plea. And “What the World Needs Now Is Love” is less a call to action than a sad cry straight from Mother Earth. Whether taking on these pop standards or belting out gospel, this quartet affirms its name with every heartening note.