As Maurice Starr was to New Kids on the Block, Simon Cowell is to Il Divo . But Il Divo – with the ages of its four members ranging from 36 to 41 – is hardly a boy band.

What they are: an international popera sensation, an act Cowell created in 2004 that’s sold more than 20 million CDs. Their last studio disc, “The Promise,” debuted at No. 1 in nine countries.

The Divo hunks wrap up a Christmas concert jaunt at the Citi Performing Arts Center Wang Theatre tomorrow. Backed by a 37-piece orchestra, they draw from their 2005 CD, “The Christmas Collection,” and sing other seasonal songs.

Il Divo’s members are Swiss tenor Urs Buhler, Spanish baritone Carlos Marin, French pop singer Sebastien Izambard, and American tenor David Miller, who called to talk about how Simon made him a star without having to go on “American Idol.”

How did this come together for you?

Miller: Simon’s people contacted my agency and said he was putting together a group. He wanted guys who have an operatic-caliber voice who are willing to not sing opera. When I met him, he was very down to earth, very practical, efficient. He was very enthusiastic and had a lot of faith in the four of us. He was hands-off. He said, “I hired you for a reason, and the reason you’re not coming out of my TV shows is I want everybody to be on a professional level. Go for it and take it to another place.”

You were an opera singer. Did you question what this was about?

To be frank, three years earlier I wouldn’t have shown up for the audition. There’s a lot of highfalutin’ snobbery that goes with opera. For a long time, I was entrenched with the idea it was the only true vocal art form. But I was in Baz Luhrman’s “La Boheme” on Broadway, and Baz completely expanded my awareness of what it means to use the classical voice, to integrate it into your emotional speech.

Who chooses Il Divo’s songs?

Same as it has always been, by democratic process. We all put songs on the table and start shooting out ideas. Sometimes, Simon would come in with a curveball, like Frankie Goes to Hollywood’s “The Power of Love.” ABBA’s “The Winner Takes It All” was another one. It really works for us. It’s very rich and lends itself to drama.