“I’ve become less interested in guitar and more interested in being a member of the band, performing, and writing good songs,” says Castro. “And when you’re playing night after night, stuff really starts to happen.”

Although Castro’s reputation is built on hot blues licks, he didn’t plan to record a straight-ahead blues album. Instead, Soul Shaker coalesced on the road, and the songs developed organically.

“We didn’t set out to make any particular kind of a record,” he explains. “We just took each song separately, and said, ‘What does this song want to sound like, and what would be the best way for the song to say what we want it to say—the feel, the attitude, the whole thing?’ Each song took a natural course.”

The opener, “Just Like Me,” is a prime example. The band—bassist Randy McDonald, saxman Keith Crossan, and drummer Chris Sandoval—played Castro’s first version several times before simply scrapping it and starting anew. Now, after almost two years jamming on the tune, it’s tight and right, with a vibe somewhere between Booker T.’s MGs and the Rolling Stones.

Although Castro is a confirmed Fender man—he says he played a Les Paul “for about one minute” when he was younger. Slinging a ’66 Strat with a rosewood fretboard, he keeps the switch set on the neck pickup, and plugs into a ’65 blackface Super Reverb.

“I do everything I can to make my Strat sound warm, and then I add the highs at the amp,” he says. “I don’t hear a lot of comments about having great chops, but I do hear, ‘Hey, you’ve got great tone!’”