Two of the burningest Zairian soukous acts are visiting Chicago within the next two weeks; this weekend it’s Zaiko Langa-Langa, who’ve been at it through various personnel changes since 1971. A recent LP on the Espera label from France reveals Zaiko to be a big, rich-sounding ensemble whose forte is lilting harmonies that build inexorably toward the requisite six- to eight-minute dance break. To my Western ears they share more with the old Congolese masters–Tabu Ley Rochereau (who gigged in Chicago last month) and the late Franco–than they do with more recent revved-up innovators like Diblo and the Kanda Bongo Man (coming here next week). The younger bands ditch the sweet balladry in favor of a harder, faster dance beat; Zaiko still plays it pretty, and their rhythmic groove retains a hint of unhurried grace that always sounds nice after a few hours of American R & B and rap. Be sure to wear comfortable shoes–this dance party could run pretty late. Saturday, 10 PM, International Longshoremen’s Association Hall, 1307 S. Michigan; 334-2293, 275-2626, 989-4440, 955-7742, or 784-4608.