The Black Keys have always posed an interesting conundrum for critics. On one hand, this is a band made up of two guys who went from riding around in a rust-bucket El Camino and earning dough performing in local country barrooms to churning out hockey stadium anthems and playing on “SNL.” On the other hand, it has never been clear just how seriously we are supposed to take their music. Most critics have been slightly dismissive of the Black Keys' tendency to work within such a limited – and somewhat dated – aesthetic sphere as rock 'n' roll blues.

On their eighth studio LP, “Turn Blue,” drummer Patrick Carney and vocalist/guitarist Dan Auerbach have one clear message: We are meant to be taken seriously. The opening song, “Weight of Love,” is an unpredictable seven-minute roller-coaster that jolts us back and forth between searing guitar lines and a spacey, ethereal backdrop. It sounds like modern Pink Floyd.

“Turn Blue,” the title track, is a bluesy, synth-driven night anthem perfect for falling asleep to. It sounds like something the Rolling Stones would have done had they only owned a laptop. And this is just what the album does so well – it unites the future with the past, taking on a new style but paying homage to classic rock greats along the way.

The album is not without personal references – the bitter aftertaste of Auerbach's recent divorce conspicuously underscores the 11 tracks. By the grand finale, “Gotta Get Away,” in which Auerbach sings, “I went from San Perdue to Kalamazoo / just to get away from you,” the whole thing can start to feel, at least lyrically, like one big hard-boiled kiss-off; some form of revenge was clearly on his mind during the songwriting. This is blues rock, however, and the Black Keys are not a group to expect much from lyrically. The duo prefers to let the music speak for itself.

At a time when most big rock reinventions are beginning to feel like clunky diversions into electronics and music without substance, “Turn Blue” provides a refreshing listen, in large part because no one really expected the Black Keys to deliver such a powerful punch after 2012's immensely popular “El Camino.” And while it may not be as catchy or radio-friendly as its predecessor, the Danger Mouse-produced treatise nonetheless proves a challenging but rewarding listen.