It's not every day that an album combining the operatic talents of such names as Plácido Domingo, Danielle de Niese, René Pape and Thomas Hampson hits the shelves - let alone a recording of pop and country tracks. But music producer Milt Okun is an influential man. In a career spanning over 50 years, the American has worked with a wide range of artists - and his ties to Domingo and to the late singer/songwriter John Denver have made possible the unlikely pairing of operatic stars and Denver songs in 'Great Voices Sing John Denver', released on June 11.

Sharing the spotlight with Domingo and co are Patricia Racette, Daniel Montenegro, Stuart Skelton, Matthew Polenzani and Chinese bass-baritone Shenyang, lending the project a truly international air, and embodying Denver’s status as ‘an international man’. Each artist has personally chosen his or her song for its particular story.

The project, which came together with the help of composer Lee Holdridge, sprung from an idea of Milt Okun’s wife Rosemary: ‘My feeling was that we had to do it,’ she says. ‘I believed that we owed it to John. Milt and I had been lucky enough to have this wonderful singer and performer in our lives - lives that John enriched immeasurably. And it was a true partnership.’

For his part, Milt Oken recognised such a recording would rest on the involvement of Domingo: ‘The instant I mentioned the idea to Plácido, he said yes,’ says the producer. ‘He and John had such a warm relationship. I remember the time when we were recording Perhaps Love in 1981 with such fondness. They hit it off immediately and just loved working together.’

'Great Voices Sing John Denver’ is released on June 11, 2013.

Listen to Plácido Domingo and John Denver's recording of Perhaps Love below: