Let's be honest: the Black Keys never really suited stadiums. Anyone who saw their intimate and incendiary early performances in the Kings Arms or the Powerstation knows their 2012 Vector Arena show was cold and impersonal in comparison, despite drawing heavily from El Camino's mainstream-smashing accessibility.
The question is, if you're a stadium-sized band and you don't want to rock stadiums any more, what do you do next?
For Akron duo Dan Auerbach and Patrick Carney, the answer is to turn off the amps. Turn Blue's mellow change of pace feels like a reaction to El Camino's stadium-filling success, a slower record that relies on the subtle and moody blueprints of producer Danger Mouse to get its point across.
That means those electrified guitar riffs that made feisty El Camino tracks Lonely Boy and Gold On the Ceiling so enjoyable are gone. There are still great tunes here - they're just packaged differently. It's Up to You Now has a throbbing bass rasp, skittery drum patterns and a ghostly howl delivered by Auerbach.
Year in Review is a slender melodrama with Auerbach's girl problems detailed over spooky choirs. And Fever has a classic Carney drum beat and a shimmering electro throb as a tired-sounding Auerbach moans, "Just go ahead and kill me".
It's a rare moment that has the sexy Black Keys swagger of old. But with barely a guitar struck in anger, things can get bogged down in introspection. Like Lovers' low-key synthy whine that doesn't really go anywhere interesting. The ballad Waiting on Words has Auerbach singing in a kind of weird faux-croon he doesn't suit.
And you're not going to jump around the room playing air guitar to the plodding In Our Prime, a smoky, orchestral-drenched downer that opens with the lyrics, "Pour me down the drain, I disappear" and never really recovers.
But the biggest sign of a Black Keys' backlash is the nearly seven-minute opener Weight of Love, a sleepy song full of acoustic guitars, hummable hooks and wandering Auerbach solos. It sounds more like an out-take from Broken Bells' last record than a statement of intent from one of the world's biggest rock acts, and will come as a major "what the?" moment for El Camino fans.
It means Turn Blue has plenty in common with Kings of Leon's 2010 album Come Around Sundown - a chance to pause for breath, reflect a little and wonder if all those stadium shows are really worth it. Turn Blue? The album's title says it all, really.
Blues-rock buddies dim the lights