The Empire Brass Quintet, Boston University's internationally acclaimed quintet-in-residence, was all sass, brass, and class at the WCRB Night at the Pops Saturday.
With Symphony Hall's new light-bulb-encrusted backdrop glinting off their horns and creamy white suits, they tooted and jazzed their way to a standing ovation with a mixed bag of pop and Dixieland hits: from ''West Side Story'' and from such composers as Cole Porter (''Leader of the Big Time Band'') to Jelly Roll Morton (''Black Bottom Stomp'') and Fats Waller (''Ain't Misbehavin' '').
A 30-second note riff from lead trumpeter Rolf Smedvig playing ''Carnival of Venice'' was the hit performance of the evening. He was backed up with aplomb by a Wynton Marsalis look-alike (and nearly play-alike), Charles Lewis. The others took turns in the limelight as well, including Samuel Pilafian playing his tuba rendition of Ethel Merman.
What makes the Empire Brass Quartet suc-cessful is its polished unity, dynamic range from mellow to brassy, and showmanship. The players don't just blow you out of the hall with high-velocity decibels: In fast-moving ''Black Bottom Stomp,'' they ended with an unexpected pianissimo. A blast from brass never fails to stir a crowd, and the Empire's high, close harmonies have the added ingredients of style and soul.