Most people have a deeply rooted fear of standing before a crowd in their underwear. Sean Tillmann actually got more nervous when it came time to wear a suit on stage.

“I was afraid I’d bitten off more than I can chew,” the Minneapolis singer better known as Har Mar Superstar said about his first-ever performance at the Dakota Jazz Club in February.

It wasn’t the fancy Dakota that unnerved the Twin Cities music vet, although he did admit, “You have to bring in a higher level of seriousness when people are dropping $200 with dinner and drinks instead of $20 to go stand in a bar.”

Tillmann’s Dakota debut also doubled as the premiere of a new act: a tribute to one of soul music’s first major crossover pop stars, Sam Cooke, whose landmark hits include “You Send Me,” “Cupid,” “Twistin’ the Night Away,” “Having a Party” and “Bring It on Home to Me.”

The daunting task of paying homage to one of the greats — “There was a deep sense of, ‘Don’t [mess] this up,’ ” he conceded — gave way to the thrilling experience of having the Dakota declare his shows their quickest sellouts since Prince played there. So they added more shows, and those sold out, too.

Things went so well that Tillmann and his band are taking their Cooke-athon on tour to both coasts and points in between in May and June, with a hometown theater gig in the works as a possible finale. They return to the Dakota for two more sold-out shows Friday night.

“Everything about this was pretty damn intimidating, so to have people respond so favorably to it was a huge relief and hugely rewarding,” the singer enthused.

And he’s happy to think that all of the positive response wasn’t just for him.

“I thought maybe I’d be turning some of my fans on to [Cooke], but everyone seemed excited about it from the start. For people my age and younger, this is a show they can share with their parents, which is a pretty enticing idea for me.”

You probably wouldn’t have guessed it when he was a young punk rocker signed to the Amphetamine Reptile label with his first band Calvin Krime — or even when he was a electro-sizzler indie R&B singer hanging out with the Strokes and Kate Moss and landing cameos in Ben Stiller movies — but Tillmann has long been a Cooke die-hard.

“I grew up in a prime time of oldies radio when he was on it a lot,” recalled the Owatonna native, who just turned 40 in February. He remembered hearing such landmark Cooke songs “on the car radio and other random places.”

“Throughout my whole childhood, I became kind of obsessed with this catalog of songs that I didn’t even know belonged to one person. And as I got older, he just kind of stuck with me, and I grew to appreciate the deeper side of him.”

Doing a Cooke tribute was a way to show off a deeper side of Har Mar Superstar, too.

At home in the range

Once a cocky alter ego of Tillmann and now more or less just his stage name, Har Mar has been flexing his soul-singer muscles since his pivotal 2013 album “Bye Bye 17.”

That throwback-sounding record included the horn-blasting single “Lady, You Shot Me,” named for Cooke’s final words as he died from gunshot wounds in a bizarre 1964 tragedy at age 33.

The album paid tribute to Cooke in an unintentional but more crucial way: “Nearly every song on that album is in the key of G, which is where Cooke usually is, too,” Tillmann said.

Turns out that most of Cooke’s songs fall into his vocal range, so singing the tunes isn’t a huge stretch, he said.

His bandmates for the shows — including guitarist Jake Hanson (Gramma’s Boyfriend, Mason Jennings), bassist Adam Hurlburt (Solid Gold), keyboardist Adam Baum (Night Moves) and drummer Ryan Mach (Fort Wilson Riot) — aren’t known for playing vintage soul music, but “everybody was super-pumped to dive in,” he said.

“We all saw this as a way to test ourselves and up our musicality,” he said. “It’s been a lot of work, but it’s pretty easy to want to do it when the material is this good.”

By design, he and the band are largely sticking to Cooke’s poppiest material and not touching on what Tillmann called “the stuff not really meant for a white dude like me to do.”

The off-limits areas include Cooke’s landmark civil rights anthem “A Change Is Gonna Come,” which Tillmann left for local neo-soul/hip-hop powerhouse Sarah White to sing at the Dakota gigs in February. He’s also avoiding the late great’s stellar gospel recordings (Cooke fronted the Soul Stirrers in the 1950s before “going secular”).

“It’s a genre I love and enjoy singing along to, but I personally don’t feel like I want to step into the religious side of things,” he said.

Not that Tillmann is discounting the “change” that Cooke helped instigate. On the contrary, he said, “That’s a big reason why I became more and more fascinated by him as I got older.

“He’s this super-accessible singer, and yet a lot of people don’t know just how much resentment he had for the establishment and for the white men in control. I appreciate how much he refused to play the game.”

That reverence is part of the reason Tillmann opted to don a suit and tie for the Dakota shows and class things up. The contrast between these tribute sets and the Har Mar Superstar live gigs of old — which often ended with him stripping down to his skivvies — wasn’t lost on him, but he downplayed the symbolism of it.

“I actually haven’t taken my pants off at a show for about 10 years, but it’s still a bullet-point kind of thing people know about me,” said Tillmann, who noted with a laugh, “I’m 40 now, and acting more like it.”

After extended stays in Los Angeles and New York over the past 15 years, he bought a house in northeast Minneapolis two years ago and leads a more settled life with a steady girlfriend. However, he doesn’t see the Cooke shows as a sign of mellowing out. In fact, he sees it as pushing himself artistically, saying, “It’s good to be scared.

“There wasn’t any grand plan behind this, like, ‘This will show ’em how much baby has grown up!’ 

“The Dakota invited me to have a show, and I thought this would be a fun way of sort of playing to the room. I had no idea it would turn into what it did, but I’m thrilled it did.”

Har Mar on his three Sam Cooke favorites ...

“Bring It on Home to Me”: “I can just really go nuts and belt away on that one. I’ve always been obsessed with songs like that, which has just one part repeated five times, but it builds and builds into an emotional crescendo. And it’s a good universal song about relationships. Anybody that’s been in the doghouse can feel what he’s singing about.”

“I’ll Come Running Back to You”: “It’s kind of the same vibe as ‘Bring It on Home,’ but a little more gentle. There’s something about it — it’s the one song that always gets stuck in my head.”

“A Change Is Gonna Come”: “It’s one of the most powerful songs he wrote, no question. The political circumstances around it are enormous. The hope through the bleakness of the lyrics is insanely powerful to me. It’s a song that just needed to be made. I heard that when Martin Luther King Jr. died, Rosa Parks listened to that song 20 times in a row to get through it. That pretty much tells you all you need to know about it.”

... And two he won’t do

“A Change Is Gonna Come”: “I just don’t think I can. It’s a beautiful song no matter what, of course, but it’s not really for us. That’s been the reaction I’ve had anytime I’ve heard a white person do it.”

“Only Sixteen”: “Not in this day and age. We were going to rehearse it, but I just decided, ‘Let’s not even go there. Way too creepy.’ He is only 17 in the song lyrics if you listen, but you’d have to explain that to the audience, and it’d just feel too awkward.”