It's been 45 years since Santana's early '70s lineup recorded together, so counting down a few more days until their Santana IV reunion record arrives on April 15 shouldn't be too difficult. But now you don't even have to wait that long: The whole album is already streaming.

NPR's First Listen has unveiled the complete Santana IV, which you can check out on NPR's site or below. The 16-song set, several years in the making, also features Isley Brothers singer Ronald Isley on a pair of tracks — an early glimpse of the full-album project Carlos Santana has been working on with Isley and Sly & the Family Stone bassist Larry Graham.

"We didn’t have to try to force the vibe – it was immense. From there, we then needed to come up with a balance of songs and jams that people would immediately identify as Santana," Santana said of the reunited lineup's first jam sessions. "When you can go back and break new ground with joy and determination – and some whoop-ass energy – it gets you going. I think we achieved something very rare. This music was screaming to come out of us. It wasn’t about nostalgia. It was about passion."

Santana will support Santana IV with a round of tour dates that started with a warm-up gig in Las Vegas last month. Visit the band's website for a complete list of shows and detailed ticketing information, and check out footage of their warm-up show.

See Santana and Other Rockers in the Top 100 Albums of the '70s