Okay, seriously: if anybody out there ever expected to hear a sitar on a Soledad Brothers album, raise your hand. Or better yet, don't - because if you did see that coming, you're either lying, or you have no clue who the Soledad Brothers are in the first place. This is, in short, the last band in the world you'd expect to throw traditional Indian instrumentation into the mix. Saxophone, sure, or wailing harmonica; maybe even a horn section now and again, but let's not get too excited. Anything beyond those basic embellishments would have just cramped the Brothers' intentionally spartan style, the raw and ready approach they justifiably call "Rust Belt Rhythm & Blues." Until now. Because The Hardest Walk, the latest and most textured release by these Detroit-via-Toronto rock 'n rollers, does contain sitar — as well as, to wit, synthesizer, lap steel, banjo, cello, flute, congas and Vibraslap.

Truth is, though, their musical evolution has been a much more gradual affair than you might expect. Right off the bat, the difference between 2000's self-titled, Jack White-produced debut and its 2002 follow-up, Steal Your Soul and Dare Your Spirit to Move, was striking; not just in terms of production values, but with the addition of multi-instrumentalist Oliver Henry, who expanded the lineup from a two-piece to a trio. Voice of Treason, which came in 2003 for UK audiences and 2004 for us Americans, was a subtle expansion of the palette, more about mood than anything else, but it continued the progress. So it should come as no surprise that The Hardest Walk represents another step forward, and indeed it is; with auxiliary support by an unofficial fourth Brother known only as Dechman (the man behind the sitar), the Soledads have pulled off an effortless balance between the familiar territory and the new.

Of course, it can't hurt that until its midpoint, The Hardest Walk feels more like a return to form than anything else. "Truth or Consequences" kicks off the record in style; with its rock-solid beat and frontman Johnny Walker's Jaggeresque drawl, it's probably their best Mick Taylor-era Stones impression since "Teenage Heartattack." "Downtown Paranoia Blues" and "Crooked Crown," on the other hand, sound like they could have fit in just fine on the Brothers' stripped-down, blues-oriented debut - and that's a good thing. Unfortunately, not all of the classic Soledad sound runs as smoothly as these highlights: "Crying Out Loud (Tears of Joy)" rides one of those languid, sexy blues grooves Walker does so well, but its appeal is hurt by one of the worst rhyme schemes in recent memory ("my hidden consolation / gets lost in your translation / upon further contemplation / I give this proclamation"). So it's probably for the best that after noise-squall interlude "White Jazz," the album takes a decided turn into unexplored territory.