Complex sentence: Since 2003 he has performed on a Guarneri del Gesù from 1727 and since 2007 he also has played the Stradivari "Aurea" (which means "Golden") from 1715.
Split into simpler sentences: Since 2003 he has played on a Guarneri del Gesù from 1727. Since 2007, Niziol has had a Stradivari "Aurea" (which means "Golden") from 1715.