When you hear that your favorite band is using strings and horns on their new album, you can pretty much assume the salad days are over. That the band you loved for years—whose lyrics you wrote down in your notebook, whose songs you choreographed secret dances to in your bedroom—is dead forever. And now you have to find a new favorite band, start at the beginning, scour the small clubs for someone with no pretensions, choreograph some new secret dances.

But when the Walkmen employed strings and horns on last fall's remarkable You & Me, they did it in the most subtle way conceivable, and it seemed to open up a door to a warmer and fuller sound. If you listen closely on headphones you can hear the violas trembling at the start of the stunning song "In the New Year," but even if you don't notice them outright you still feel their presence, like a blanket of lightning bugs just outside your periphery.

In some ways the Walkmen have progressed stylistically backward from how most bands evolve. Usually a successful band starts with a rough sound and a lot of heart and integrity, manages to get things together by the third album, has one song coalesce into a big radio hit, and then follows that with a lot of empty striving for wider success in musical styles that are currently popular. The Walkmen had their hit, "The Rat," on their second album, but then started to turn away from striving to keep up with contemporary bands like Franz Ferdinand. Now their music seems to have more in common with Elvis Presley and Roy Orbison; classic and simple rock 'n' roll with big soaring crescendos. The lyrics too have become less concerned with saying something hip or dissing anyone, and more intent on expressing tenderness and hopefulness. You would think that some remarkable, life-changing event happened to lead singer Hamilton Leithauser. A car crash, perhaps. Or maybe he saved someone from choking.

"There wasn't any moment or event that changed our attitudes," he says via email. "I think we were all just in a good place while we made this record, which is ironic because our label had basically told us to buzz off, our manager basically walked out, and people were running for the hills all around us."

Leithauser puts more energy into singing every single syllable—even the consonants—than anyone has since James Brown, but without expending any effort at all on dancing, or even so much as tapping a foot. He stands tall on stage, and looks above the audience while he grips the mic with the cord wrapped around his hand, like he's a bully looking for someone to fight. But now the words that echo through song after song are declarations of love, often simply just, "I do, I do."

"I think You & Me was a big step forward," he writes. "It didn't seem like we ever had any interest in writing pop songs back then, but I guess people were always begging us to cut 'The Rat' down to three and a half minutes. Maybe if we had we'd all be driving Bentleys instead of VW Golfs."

Maybe Bentley salesmen and the old record label are the only ones who would be disappointed by their decision. Music fans, romantics, choreographers of secret dance moves... all of us are happy to have one more great album from our favorite band.