When the Doobie Brothers opened for Santana at Blossom in 2019, they delivered an opening set laden with their hits from the '70s. A vibrant saxophone solo put a punctuation mark on a rousing rendition of “Without You,” and the band played “China Grove,” a track that featured pitch perfect harmony vocals, with a real fierceness. Expect something similar tonight when the classic rock act returns to Blossom at 7. Keyboardist Steve Winwood shares the bill.