X, the highly touted Los Angeles rock quartet, appeared at the 9:30 club last night amid great expectations. The actual experience was partly exothermic, partly exaggerated and wholly exhausting. For one thing, X doesn't just mark the spot, it hits with almost excessive structural tension and exceedingly loud sonic excursions. This can be exasperating because many of the songs on their two albums are exceptionally astute expostulations and examinations of the brutal urban angst and generational exorcisms prevalent in California.

Ironically, X's once anarchic stage persona has been excised in favor of leaner power chords played in clean overdrive. Their troubled scenarios and dark themes are no less effective, though there are now suggestive echoes of the Doors and early Jefferson Airplane on speed.

The anthemic hardness and tensions are marred only by the genre's ongoing problem -- excruciating sameness, with interesting songs extirpated by X's wall-of-sound-over-substance delivery. Their considerable enthusiasm and energy end up being short-circuited by the exaggerated and frenetic pulse and by lead singer Exene's curiously offhanded vocals, which come across somewhere between a blur and a blood-curdling scream, particularly when she joins bassist John Doe on atonal harmonies.

In another vein, guitarist Billy Zoom (who is almost too good for this group) powers the music with a style rooted equally in Chuck Berry and Eddie Cochran's exuberant rawness, while Doe and drummer Don Bonebrake exchange bottom-line exhortations. The capacity crowd, as expected, was ecstatic, getting exactly what they were looking for -- an explosive exercise in excommunication, L.A. style.