At 38, Brett Dennen probably doesn't need to be told how boyish he looks and sounds.

With his thick shock of red hair, youthful features and tenor voice, yes, he could easily pass for a decade, or more, younger.

But once the soulful music starts pouring forth, his seasoned maturity as a singer-songwriter is established, quelling all premature assumptions of callow youth. 

Dennen, making his downstate debut in a Castle Theatre concert at 8 p.m. Tuesday (also with Aussie singer-songwriter Dean Williams), is in the midst of his "Let's ... Tour," timed to the mid-February release of his EP of the same name. 

The closest he remembers coming our way before was after a Chicago date several years back when a buddy "invited me down" to visit. It was about two hours south ... but I don't think it was Bloomington ..."

Dwight? Pontiac? Chenoa?

He's not sure, but he's more than happy to be staking out some new territory along those lines.

"Let's ..." is a title that urges the listener to join in with Dennen on the activity of his or her choice ... be it having a good time or simply communing on a kindred wavelength.

"For me, it's more like an invitation to do something, anything, together."

He calls it the "first half of a whole album," referencing a second EP that will come later this year.

Instead of two halves to make a whole, why not just issue a one dozen song album and be done with it?

"I wanted to do a prolonged tour that would allow me to get to some of the smaller places like Bloomington, and not just play the major markets," says Dennen.

By breaking the album release in two EP halves, he'd be able to sustain the excitement of the tour with two servings of new music. "The record label was cool with it, and the two halves will be released as a whole album eventually," he promises.

Dennen, famously upbeat and pro-social-change, came of age in central California, where he was home-schooled and urged by his parents to indulge his natural music leanings.

His professional career began in 2004 with the release of his indie-produced self-titled debut album.

Withing a few more years, he'd attracted the interest of John Mayer, who invited Dennen to join his 2008 tour. That year, his song "Darlin' Do Not Fear" was added to the soundtrack of the award-winning indie film "Sherman's Way."

That usage set a precedent, with Dennen's music periodically turning up on TV and film soundtracks, including his "Comeback Kid (That's My Dog)" being selected as the theme song for NBC's "About a Boy," the series version of the hit movie that aired in 2014 and 2015. The series "Parenthood" has also tapped the Dennen catalog on multiple occasions.

Is he as upbeat as the usage of his music makes him out to be?

"Well, that's one side of my personality on stage because when I perform I prefer to make music that I prefer to be positive and fun ... I want the world to be a happier place, that's all. I'm not saying that I'm changing the world, but I have too little time to make people feel bad."

Despite all the bad karma presumed to be in the air these days, Dennen says the net effect has titled in in his favor.

"This is the perfect time because, now more than ever, people want to be around positivity. I think that this feelings of desperation, isolation and depression that people talk about come from a desire and longing to be included ... to belong to something and be part of a community."

Enter the healing power of music ... be it his or someone else's.

"I think I have a lot to be happy about, even though I've had my fair share of sad times, that's for sure, and I've written songs about them. But they never sound as good as the happy ones."