Keith Klassen has emerged to become one of Canada's busiest tenors, averaging 12 productions a season since graduating with honours from the Opera Division at the University of Toronto in 2002. He has been engaged across Canada, as well as in Scotland, Germany, the United States, Ireland and the Czech Republic. The Star Phoenix described him as having, "...a big ringing voice and great stage presence", Classical 96.3 added, "Klassen's voice is pure honey with its ease of high notes and the lyrical grace of his phrasing.", Opera Canada raved that his Rodolfo was "...dramatically convincing, sung with passionate sincerity ensuring the audience's love.", John Terauds of the Toronto Star called him, "...one of the country's most versatile artists.", and NOW magazine's Jon Kaplan went so far as to rate Keith as one of Toronto's top ten theatre artists of 2006.
In the past season alone, critics and audiences alike have enthusiastically received his performances of Rodolfo (La bohème), Alfredo (La raviata), Don Jose (Carmen), the Duke (Rigoletto), Samson (Samson et Dalilah), Uriel (Haydn's 'Creation') and Spoletta (Tosca). Keith has also continued his work with Tapestry New Opera Works, joining their newly formed studio company.