CD. For more than 20 years, every Caspian album has been driven by a desire to stretch boundaries - a relentless ambition that's resulted in one of post-rock's most revered catalogs and established the Massachusetts quintet as an enduring, global force in the genre's modern era. On Caspian, the band's first album in six years and debut for Wax Bodega, the more unexpected way forward was to stop searching for what they hadn't yet done and instead trust what had defined them from the beginning.The six-song, 39-minute effort draws freely from the musical vocabulary the band have spent their career writing: evocative melodic themes, dense textures, swelling crescendos and crushing heaviness that rolls in like a slow-moving storm on the horizon. But they still find new possibilities within those familiar contours, allowing patient development and repetition to carry as much weight as surprise. The nine-minute "Remain" turns a recurring melody into a sweeping study in tension and release, while "No One Left to Tell" layers subtle shifts around a hypnotic tremolo figure and "A Great Fire" sends serpentine guitars crashing into buzzsaw riffs. Even the graceful 3/4-time closer "Waltz for the End," completed in a half-hour burst of inspiration, reflects the quiet confidence of five musicians comfortable enough in their skin to resist tearing everything down for the sake of reinvention, even as the circumstances surrounding them change dramatically.