Dan + Shay are obsessed with the plus sign.

Not only is it part of the moniker of country music's hottest duo, it's their de facto logo, an icon on much of their merch (dig those socks covered in ++++), and the shape of their satellite stage on Saturday night at sold-out Target Center in Minneapolis.

The plus sign is useful in explaining Dan + Shay's success as Grammy-winning, chart-topping recording artists: heart-tugging lyrics + lush harmonies + remarkable hair + dark-haired handsomeness.

The plus sign also can be used to explain their successful debut as arena headliners: incurable romanticism + boundless energy + eager-to-please enthusiasm + imaginative production.

With his luxe tenor, Shay Mooney possesses the prettiest male voice in Nashville since Vince Gill, only with more range and depth. He sounded almost Freddie Mercury-like on "I Should Probably Go to Bed" and soared on the choruses of "Speechless," the duo's defining power ballad, filled with lyrics about love, romance and devotion.

Mooney was much more physical and demonstrative than at the duo's 2019 performance at the Armory in Minneapolis. It was pretty obvious at Target Center that the lead singer, 29, had tons of brotherly love for Dan Smyers, 34, the songwriter, multi-instrumentalist and producer who provided vocal harmonies and played guitar and piano onstage.

On Saturday, the overly exuberant Smyers tried hard to play the casual rock star, with tight jeans, a Prince & the Revolution T-shirt, and Robert Plant hairdo circa 1974, fluffed by a floor fan like Beyoncé uses in concert.

A hypeman with oodles of energy, Smyers might have barely edged Mooney when it came to ingratiating comments. How many times can you tell 14,000 fans that they are the loudest singers and craziest audience ever? The Prince T-shirt was a nice nod to Minneapolis but then switching to a Vikings tee at intermission and touting his next-door neighbor in Nashville, ex-Viking Jared Allen, seemed unctuous.

Speaking of intermission, it was one of the few minuses in a show filled with pluses. Since there were two opening acts, the break just one hour into Dan + Shay's set seemed unnecessary, especially since Act II — a nice balance of stripped-down tunes and big full-band hits — was only 40 minutes long.

Otherwise the production was impressively creative for the pair's first foray at headlining in arenas. The plus-shaped stage in the middle of the venue that was used for the opening and two other segments added both intimacy and variety. The main stage was minimalist, with four backup musicians on risers and a triptych video wall featuring lyrics, live video and appealing graphics.

Even if their musical aesthetic is more Air Supply (the 1980s yacht rock duo) than Brooks & Dunn (the enduring country pair), Dan + Shay have the right instincts when it comes to entertaining modern-day country crowds. Give them one more plus — a B+ — for their first arena tour.

Colorado-reared singer-songwriter Ingrid Andress offered one of the more emotional opening performances witnessed in an arena. "Thank you for making me cry for the first time ever onstage," she said after her fifth and final song.

What happened was when she sang her hit "More Hearts Than Mine," about how a romance involves relationships with a woman's entire family. The crowd spontaneously held up lit cellphones. Her parents, who live in Grand Marais, Minn., were in attendance.

"That has never happened to me before," Andress said at song's end. "That was pretty beautiful. I think I'm going to retire now."

She probably shouldn't. With pop songs that evoke Sara Bareilles, Andress has a promising future, whether in country or pop.