Pestilence's fourth and final album, 1993's Spheres, was an inspired but divisive affair, broadening their creative horizons to the brink of death metal's acceptable limits while alienating their audience at a time when heavy metal in general found itself in a no-win situation, no matter how inspired.

On Spheres, Patrick Mameli's vocals were still 100 percent melody-free and crusty in the extreme, but bona fide death metal guitar crunch was significantly scaled back to make way for pervasive synthesizers, spinning spidery strands throughout the album's best songs -- much like Cynic's Focus CD that same year, in fact, minus the equally synthetic robo-vocals.

And yet Pestilence's risk-taking really paid off on these cuts (namely "Personal Energy," with its division bells forewarning of progress, the aptly named "Changing Perspectives," and the title track), which turned out as appealing and memorable as they were unorthodox.

Too bad they were all shoved into the album's second half, while the first was packed with significantly harsher but halfhearted and unfulfilling hybrids like "Mind Reflections," "Multiple Beings," and "The Level of Perception" -- presumably ordered that way in a failed attempt to appease the band's death metal hard-liners as they were drawn into Spheres' drastic innovations.

And, showing how close was the fraternity of progressive death metal bands of the period, shorter ambient pieces such as "Aurian Eyes," "Voices from Within," and "Phileas" resembled similar detours placed by death-jazz supremos Atheist on their final LP, Elements -- also released in 1993.

Come to think of it, these three likeminded bands' simultaneous experimentation and extinction pretty much proves that the average death metal fan was simply unable -- or unwilling -- to accept such daring sonic evolution.

And so, Spheres unfortunately signaled the stillborn death of a promising subgenre, as well as Pestilence's career, but it's no wonder that the album remains a cult favorite among those by bands as different as Daath and CKY.