rog rock is dangerous terrain. Step one way, and you fall into the wretched excess of Emerson, Lake & Palmer. A misstep another way leads to the interminably turgid Dream Theater. Abandon all hope (of meeting girls), ye who listen to Yes! The problem with prog is self-indulgence; the genre brings to mind guys with ponytails who sit around and praise Rush for its "musicianship." But now that bands like The Mars Volta (and in the past, Built to Spill) has made prog less unhip, Dysrhythmia should find fans outside the usual long-haired circles.

This instrumental trio has what most prog doesn't: restraint. No note is out of place, and the group eschews "jamming" in favor of tight but adventurous composition. Bassist Colin Marston and guitarist Kevin Hufnagel are virtuosos; Marston moonlights in avant-prog metal band Behold…the Arctopus, while Hufnagel is trained in jazz and classical guitar. But despite its technical bent, the group knows how to groove, and concisely conveys its chops without sounding studied.

After two self-released recordings, including the phenomenal No Interference, the band signed to grind/death metal label Relapse Records. The pairing might seem odd, but the band's chops match or exceed those of anyone on the label. In 2003, Dysrhythmia recorded Pretest with Steve Albini, who captured the band with his signature "live in the room" sound. Albini was a good choice; he recorded The Jesus Lizard's best albums, and at times Dysrhythmia sounds like The Jesus Lizard playing instrumental surf rock filtered through the prog metal of Atheist and Cynic.

On Barriers and Passages, Martin Bisi (Sonic Youth, Dresden Dolls, Helmet) is behind the boards. His work is so stellar that the album's promotional sticker hypes his role as engineer. Albini brought out Marston's huge, distorted bass tone and Jeff Eber's tough, yet supple drumming (again, think of The Jesus Lizard's rhythm section), but Bisi adds more clarity and detail. A notable difference from Pretest is the greater use of overdubs. They don’t often happen, as Hufnagel's playing is so full-bodied that he already sounds like more than one guitarist. But when they do, overdubs allow sustained melodies to soar over staccato, Duane Denison-esque chords on "Seal/Breaker/Void," and crystalline harmonics to chime over the wall of noise that ends "Sleep Decayer."

That song is noteworthy, both for its twitchy double-time and growling half-time passages, and for its technical prowess. Three minutes in, Hufnagel plays what sounds like a drone, but what is actually a single note picked repeatedly. He continues for two and a half minutes, picking sixteenth notes until the end of the song. That's endurance.

Hufnagel's basic tone is twangy (imagine Dick Dale, but tougher), but he liberally dials in both clean tones and muscular distortion, resulting in the band's most diverse album yet. While Dysrhythmia's music is challenging, close inspection reveals kindred spirits; Touch and Go, classic Dischord (the band has covered Fugazi live), Joe Satriani (minus the populist tendencies), Trenchmouth, The Mermen, and Mastodon all inhabit the same constellation of controlled dissonance.