Complex sentence: Sinaisky was Chief Conductor of the Latvian Symphony Orchestra (1976-87), then became Music Director and Principal Conductor of the Moscow Philharmonic Orchestra from 1991 to 1996.
Split into simpler sentences: Sinaisky was Chief Conductor of the Latvian Symphony Orchestra from 1976 to 1987. He served as Music Director and Principal Conductor of the Moscow Philharmonic Orchestra from 1991 to 1996.