IX Equilibrium is the third studio album by the symphonic black metal band Emperor. The band had stated that they were to "return to their roots", and the music presented showcases some of the band's darkest and most vicious material, as well as their cleanest production at the time. Still, it is quite different from earlier releases, featuring a mix of clean and black metal vocals, soothing symphonic interludes and unrelentingly crushing guitar work.
Eduardo Rivadavia of AllMusic describes the album as a "sonic onslaught of nearly impenetrable proportions". He noted that drummer Trym "doesn't so much keep time as pummel his kit incessantly", while guitarists Ihsahn and Samoth "contribute an equally oppressive wall of sound laced with keyboard textures so demonic they were seemingly concocted by the great horned one himself."
He concluded, "Far from a masterpiece, but hardly a stinker either, IX Equilibrium falls quite short of the group's earlier albums through sheer lack of diversity, and will prove indigestible to all but the most committed black metal fans."