Russian Circles' music never runs so much as tiptoes. Like a skilled trapeze artist, they've delicately walked the line between prog-metal and post-rock since 2004's debut full-length, Enter, an album that literally invited you into the convoluted psyche of a band that went from soaring, noodly guitar one minute to crushing, deafening breakdown the next – all within the same song. Tired of the balancing act, the Chicago trio adopt a disparate, linear slant on their fifth LP, Memorial, with divisive results. As it turns out, writing one-dimensional music grounded in singular interpretations of "post-" classifications may prove more palpable, but not more compelling.

Upon initial listen, the evidence supporting this charge is the absence of communicative acrobatics that used to parlay Russian Circles' aesthetics: pinpoint turns, ebb-and-flow dynamics, genre synthesis. On Memorial, songs don't experience discursive, myriad emotions; rather, they are one expression on a horizontal spectrum, and that feeling is usually pretty heavy. "Deficit" is a relentless, uncompromising workshop that trades apocalyptic diligence for chugging contrition – opposite sides of the same heavy metal coin. "Lebaron" demonstrates just how earth-shattering low bassist Brian Cook can go, while the sludgy "Burial" delivers an unapologetic aural assault. Make no mistake: these are sonically dense songs, which could have been victimized by unintended coalescing if it weren't for drummer Dave Turncrantz's superb sense of rhythm, forgoing the usual litany for more variable patterns.

The other half of Memorial is moodier, but witnesses an audaciously complicit co-opting of highly recognizable elements of post-rock for ostensibly insular songs. The eerie "Cheyenne" displays Russian Circles' knack for building sustain. Guitarist Mike Sullivan weaves a lush tapestry using multiple ethereal tones, scarce piano, and haunting Godspeed You! Black Emperor-esque strings. The carefully constructed edifice is all but ready to collapse before finally releasing, unraveling into an exanimate, droning void. Circles juxtapose with "Ethel," a mid-tempo jogger that opens with the faint hum of picked harmonics over sanguine guitar thrum vis-à-vis Explosions in the Sky, which melt into a sinuous melody. Similarly, the strings-only opener "Memoriam" relays a slow, repetitive guitar phrase as violin contributes necessary depth. Credit to producer Brandon Curtis, as his presence truly shines on these tracks – not because his contributions are the most visible, but because they are the most powerful.

Then there is "Memorial," the title track and album closer that threatens to kill the momentum Russian Circles spent the past half-hour creating and modifying. A pondering, celestial number featuring guest vocals from singer/songwriter and labelmate Chelsea Wolfe, "Memorial" comes off derivative (Empros, anyone?), and its inclusion is pretty weak: according to Cook, the band were trying to create a continuous, holistic listening experience, opening the album with "Memoriam" and ending with an evolved reprise. In this case, evolution apparently means "cloudy" and "misdirected."

The simpler, divided approach could warrant criticism of creative dearth; however, considering Russian Circles' pedigree (former members of Dakota/Dakota and These Arms Are Snakes), it's more likely for tangentiality: the album's dualist structure allows each composition to breathe, fully revealing itself before moving to the next, categorically different iteration. Still, when the band try to walk a genre-defying tightrope, the interplay works to hide some of their less desirable tendencies, and produces much more enjoyable, determinative music.

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