Diamanda Galas took the stage at the Wiltern Theatre last week with the robotic grace of a sleepwalker. Clad in black leather, Vampira coif around her shoulders, the spine-chilling virtuoso delivered a short, relentless set. Seated at a grand piano, she could have been the evil twin of pop star Tori Amos, albeit with none of that strawberry blonde's trademark piano-bench-bump-and-grind.

Galas, an intentionally difficult performer, rose to fame for her AIDS-inspired Plague Mass in the mid-1980s. Her work is clinical, both in its portrayal of pathological mental states and its almost scientific experimentation with the limits of the human voice. Galas unerringly seeks the most difficult registers-a little too low, uncomfortably high, shrieking, braying, half-strangled. On one bluesy song of lost love, her voice gurgled as if through a mouthful of spurting blood. Her most frequently used vocal inflection was halfway between Ethyl Merman and a tortured farm animal.

Experimentation extended to the piano, with an electronic "whammy bar" effect that hauntingly bent and flanged the chords. On another number, a country death song, she slammed her hand roughly against the piano, the echoing thud simulating a coffin nailed shut.

Songs ranged from her original torture chamber music to Johnny Cash's casually ruthless Death Row tale, "25 Minutes To Go." She switched vocal styles from line to line, as if channeling dozens of psychotic souls. Galas is the undisputed queen of dark territories, delivering lines such as, "Take me as your slave/Save me from an early grave," with a curdling undertow of passion.

One song, however, a gut-wrenching Spanish lament, was performed in a simple, moving manner. It made one wish that some kind grandmother would nag her, "You have such a lovely voice, Diamanda, why do you want to shriek like that?"

The crowd, mostly verbena-scented young Goths, enthusiastically cheered Galas on for three encores.