Founded in 1975, the Amadeus Choir is now under the direction of Conductor and Artistic Director Lydia Adams. The Choir has become known for its professionalism, exceptional musicality, and diverse, high-quality programming - all a reflection of the leadership provided by Dr. Adams. During her time as Conductor and Artistic Director (since 1984), the choir has grown significantly in size and reputation to become one of Canada’s pre-eminent choral groups. The Amadeus Choir performs a regular series of concerts at carefully selected downtown Toronto venues, presenting well-known artists in works by Canadian and international composers, including major works with instrumental ensembles or full orchestra, as well as challenging a cappella performances.

In 1987, Lydia Adams created the Amadeus Choir’s annual Christmas Carol and Chanukah Song Writing Competition. The Competition has grown over the years to include submissions from around the world. It now serves as an inspiration to composers of all ages and experience to write new works, enriching Canada’s outstanding choral tradition. In 1994 the Choir recorded Ring-a the News!, which featured a number of winning carols from this Competition.

The Amadeus Choir regularly competed in the prestigious biennial CBC Choral Competition, winning awards in 1992, 1994 and 1996 before becoming ineligible due to the Choir's semi-professional status.

In 2000, the singers traveled to Alberta on their first tour, and were enthusiastically received at each of their concerts. They performed at two prestigious festivals (ACCC and ISME), and took the opportunity to launch their CD, Songs of the Spirit, featuring works by Canadian composers Eleanor Daley, Srul Irving Glick and Barry Peters, and a work by Andrea Gabrieli, Missa 4 Vocum, which had just come to light after 300 years. This CD was given the biennial award for “Outstanding Choral Recording” 2001-02 by the Association of Canadian Choral Conductors.

The Choir's CD, Voices On High, a combined project with the Hannaford Street Silver Band, was released in 2002, and features music by recent Juno Award winner Bramwell Tovey, Harry Somers and Stephen Chatman, conducted by Bramwell Tovey and Lydia Adams. Also in that same year, Dr. Adams conducted both the Amadeus Chamber Singers and the Elmer Iseler Singers on the CD Everlasting Light – Footprints in New Snow, featuring the music of Christos Hatzis, available on the CBC Records label.

In 2006, the CD The Tokaido – The Choral Music of Harry Freedman was released by the Canadian Music Centre, and featured the Amadeus Chamber Singers, Elmer Iseler Singers, and Aeolian Winds, all conducted by Dr. Adams.

In 2008, the Choir toured once again, traveling to Sackville, New Brunswick to perform at ‘Podium’, the ACCC (Association of Canadian Choral Conductors) biennial conference, and then on to Antigonish and Glace Bay, both in Nova Scotia.

In addition to the Amadeus Choir’s regular concert series, the choir takes an active role in Ontario’s choral community by working in collaboration with other prominent local ensembles, such as the Elmer Iseler Singers, Bach Children’s Chorus, Toronto Symphony Orchestra, Hannaford Street Silver Band, Gryphon Trio, and True North Brass.