[3] Magnus first started singing in a fourth grade choral concert when she sang "Tomorrow" from the play Annie.

[4] She also previously fronted an alternative rock band called Lunar Valve, also consisting of Ralph Bousquet (lead guitar), Matthew Kohler (bass), and Jordan Bonina (drums).

[7] When the drama club was filmed for an internet reality show by Warner Brothers,[8] she was featured as one of three Dorothys for the play The Wizard of Oz.

In May 2008, in a local profile about Magnus's singing talent, the music department chair of her school district was quoted as saying "Hands down, I think she'd win 'American Idol'.

[6] Magnus auditioned for American Idol in the summer of 2009 in Boston,[13] and was one of two Massachusetts contestants to make the semi-finals of the show.

Magnus' vocal range and dramatic performances prompted judge Kara DioGuardi to compare her to Season 8 runner-up Adam Lambert.

[21] She visited the house a second time with the Top 10 contestants, and sang many songs, including "Wicked Game", "No One", "Creep", and "Umbrella".

[23] Magnus returned to the finale of American Idol on May 26, 2010, and sang "How Deep Is Your Love" with Aaron Kelly, who were both joined by the Bee Gees.

[32] On July 8, 2014, during Boston's Heaven on Earth Tour to support Life, Love & Hope, Magnus performed "Walk On" in Buffalo, New York, on July 22 at the Sandia Casino in Albuquerque, New Mexico, on August 5 at the USANA Amphitheatre in Salt Lake City, Utah and on September 3 at the Ford Idaho Center in Nampa, Idaho as a lead and backup vocalist.