Complex sentence: As the folk scene quieted, a new generation of folk-rockers took Guild guitars on stage; the most notable Guild performance of that era was the D-40 upon which Richie Havens opened the Woodstock Festival in 1969.
Split into simpler sentences: As the folk scene quieted, a new generation of folk-rockers took Guild guitars on stage. The most notable Guild performance of that era was on the D-40 that Richie Havens played when he opened the Woodstock Festival in 1969.