Josh Groban may have the voice of angel, but on his latest album he’s revealing his darker side.

The singer told Billboard that classic rock artists like Led Zeppelin, Jethro Tull and Fleetwood Mac were a big influence on his upcoming record, All That Echoes, due out February 5.

For Josh the hope was to expand his sound and get out of his comfort zone for his sixth record.

“I was concerned that the music have a little pop or rock edge to it — whatever world I find myself in, it’s just gotten really soft,” he admitted to the mag.

On the album, Josh covers Stevie Wonder’s “I Believe (When I Fall in Love It Will Be Forever)” and “Falling Slowly” from the movie, Once, along with Dave Matthews Band’s “Satellite,” available as a bonus track on the record’s deluxe edition.

But even though Josh’s latest was produced by Rob Cavallo, who has previously made albums with the Goo Goo Dolls, Adam Lambert and Green Day, the singer says he’s not completely leaving his classical roots behind.

“I’m not saying what I’m doing is Pearl Jam,” he said. “But it can have the right energy. The intent can be the same.”

- Shannon Carlin, Radio.com