For the sixth album of his songbook era, Rod Stewart softens his trademark rasp while paying tribute to soul music. He lovingly tousles the Sam Cooke hit “Wonderful World” and recasts the Motown snap of “It’s the Same Old Song” as a torchy ache before tapping its party potential. Stewart also teams up with some of the original songwriters (Stevie Wonder, Smokey Robinson) and turns in silky duets with Mary J. Blige and Jennifer Hudson. He even dabbles in disco with the effervescent “Love Train.”