Tambersauro is one of the most inwardly motivated and intelligent indie-rock bands in Houston, which, considering it's up against the likes of Motion Turns It On, By the End of Tonight and Balaclavas, is really saying something. Theories of Delusional Origin is the math/prog trio's most subdued recording thus far. The style — long, thorough suites of riffs — has not changed since 2005's Box=Box, but the elements of hardcore that marked, in particular, last year's single "One Picture Frame and One Half of a Picture" have been largely excised. This band suffers from an allergy to the obvious, shunning not only pop-song structure but also anything ­attention-grabbing like speed or volume, and even relatively recent conventions of math-rock and post-rock. What's left is an unhurried dissection and examination of post-punk rock that calls on everything from echoing space-rock ("Theories Upon," "Blue and White Fragments") to dissonant, polyrhythmic assertions ("Mitties") to wistful emo-core riffing — often all in the same song, as in "Make Water Sand." Bassist Jeff Price and drummer Lance Higdon's lyrics have an implicit and plainspoken spirituality or religiosity that sits well atop the contemplative music. Price shades toward self-pity on the album's closer, "Over and Down," but no more than is common in post-hardcore rock. The biggest strike against Theories is sound quality: Guitarist Mike Blackshear comes off well, but Price's bass sometimes lacks definition, and Higdon's drums are thin. Even so, the simplicity of the record's production makes the group's flowing, expressive interplay impossible to miss.