Three years removed from Layla and a moonlighting gig as sideman for Delaney & Bonnie, Eric Clapton itched to change up his sound in 1974. Inspired by the likes of The Band and his then-new songwriting collaborator J.J. Cale, he entered the mid-decade bathing his roots in gospel, R&B and reggae. And while blues purists accused the guitarist of going pop, the music he created in Miami, Fla., at 461 Ocean Boulevard has aged beautifully these past 40 years. Give Me Strength digs deep into this most pivotal period in Clapton’s history, offering expanded editions of that classic second solo album whose title is the address of its genesis as well as its follow-up, 1975’s There’s One in Every Crowd (which houses a killer previously unreleased cover of Peter Tosh’s “Burial”) and the Tom Dowd-compiled live LP E.C. Was Here. But the real gems on this set are on the back end of the box, where disc five offers a collection of outtakes from the E.C. source tapes and the sixth CD is a brain-melting jam session with longtime Clapton hero Freddie King at Criteria Studios, climaxed by a 21-minute ramble through King’s “Gambling Woman Blues.” If the 1960s saw Eric Clapton earn his master’s in the blues as a member of The Yardbirds, the Bluesbreakers and Cream, then the period explored in Give Me Strength shows his post-grad doctorate work in exploring the soul of his craft.