Julius Hemphill, who often dons a tuxedo when performing as a member of the World Saxophone Quartet, showed up at d.c. space Saturday night wearing a red baseball cap, T-shirt and sunglasses. He was clearly relaxed, as were the other members of his current quartet, but the opening set quickly developed as much tension as release.

The performance, which included five extended pieces by Hemphill, frequently reached a feverish pitch. With its sharp and sometimes strident tone, Hemphill's alto saxophone would seize the moment and bring it higher, boosted--more often than not--by enormous percussive thrust: the sudden detonations of drummer Pheeroan akLaff; the nudging accompaniment of conga player Jose Garjalef; the percolating electric bass patterns of Jerome Harris, and the spiky, nonchordal accents and myriad tonal effects employed by guitarist Bill Frissell.

Frissell and Hemphill work particularly well together--not only on the freer numbers, where their instruments occasionally embraced to produce a single tone, but also on the ballad "Testament No. 5" and the loping Texas blues "Border Town," where they played complementary roles.

During all of this, Hemphill's direction wasn't always clear and the sense of groping common to progressive jazz was certainly evident at times. But mostly the performance expressed human emotions in refreshingly unvarnished ways.