Former American Idol contestant Adam blasted the makers of the big screen adaptation for casting Hollywood stars instead of professional singers, and said vocals should have been recorded in a studio rather than performed live.
Russell - who plays Marius Pontmercy in the film - tweeted: "I don't disagree with Adam.
"Sure it could have been sweetened, [director] Tom Hooper wanted it raw and real, that's how it is."
Russell later tweeted a link to a YouTube clip of a New York family in tears after watching the movie. He wrote: "Classic ... Video of family crying after seeing Les Miserables becomes internet sens(ation)."