Prong's Tommy Victor recently remarked that metal bands can't play in standard E tuning anymore because they'd "sound like the Eagles." Not that they ever had anything to worry about, but about midway through Meshuggah's career, the band's guitarists switched from using already-low 7-string guitars to an 8-string approach in the monstrously low keys the band still works with today. Strangely, though, you could argue that the revered Swedish death/math-metal institution sounded heavier before putting out the 8-string albums Nothing and Catch 33. Thankfully, on obZen, the band continues in the repetitive, low-droning vein of those two albums but also recaptures much of the frenetic energy that made earlier releases like Destroy Erase Improve so thrilling. As much as Meshuggah re-wrote rules and forever changed the face of metal, the band appears to have settled into a comfortable groove. That's not to say that Tomas Haake and company don't strive to create something fresh every time, but they've defined their parameters by now. obZen bodes well for the band's future because of its high energy level. The album never plods; in fact, it presents Meshuggah at its most hypnotically repetitive and engaging.