The first time Clifton Duffin Jr.’s parents heard him sing was at an “American Idol” audition last fall at Chicago’s Adler Planetarium.

The 23-year-old singer from Country Club Hills, a student at DePaul University, not only impressed them but apparently the celebrity judges as well. They sent him to the Fox television show’s next round in Hollywood.

“Whenever he did sing, it was away from home or somewhere we couldn’t hear,” his mother, Sasha Duffin, said. “He just blew us away.”

To clinch his ticket to Hollywood, Duffin sang his mother’s favorite song, Luther Vandross’ version of “Superstar,” as his mother and father, Clifton Duffin Sr., watched.

His move to the next round doesn’t mean he’s in the finals, but he is a step closer than thousands of others.

During his audition, which aired last month, Duffin sang “Who’s Loving You” by the Jackson 5. Then, he said, the judges wanted to hear another song.

“I went completely blank,” Duffin said. “All I could think of was ‘Superstar’ by Luther Vandross. My mother had been playing that a few days prior.”

He nailed it, the judges said, and he’s still in the competition.

The “Idol” hopeful says he’s having a blast. His cell phone was swamped with calls and text messages after his Jan. 17 appearance, he said.

“That was a lot of fun. It was so amazing. I literally couldn’t answer my phone. The messages were pouring in. I never expected that,” Duffin said.

When he was singing, his parents were silently watching and listening.

“It was a shocker to hear him,” his mother said. “I became overwhelmed. It hit me so hard. We’ve watched it again, and I’m still shocked.”

Duffin’s eager to get to Hollywood.

“Getting this far is validation I’m good enough,” he said.

Duffin may have a long way to go, but he’s confident. Nevertheless, you won’t catch him singing on campus.

At least not within anyone’s earshot.

“I sing when nobody is around, if I’m driving somewhere or walking in the park or when I’m alone. My heart is in the music. Performing is a passion of mine, but I still don’t practice in front of people,” he said.

Duffin, who graduated in 2006 from Hillcrest High School, where he sang in a choir, is a junior at DePaul, where he studies computer engineering, public relations and advertising.

Sounds like he’s doing well in public relations, as he has nothing but praise for “American Idol” judges Randy Jackson, Keith Urban, Mariah Carey and Nicki Minaj.

“Those four? They were honest and surprisingly great. You hear a lot in the news about them arguing, things like that, but they were amazing,” he said. “They allowed me to have fun. They told me the talent is there, to trust my instincts and to believe in myself.”

Whatever happens, he’s already won over one judge.

“Oh, my goodness,” his mother said, “am I proud.”