She may come off a little bit country, a little bit rock ‘n’ roll, but when Grace Potter belts out her lip-quivering squeal at the anchoring pinnacle of each harrowing love song, she hits right at the soul. After coming out of the shadows of dusty record bins on two prior albums, Potter and her Vermont-based band the Nocturnals got a fresh coat on their 2010 self-titled release, whose continual play on Top 40 stations spun like a pottery wheel giving the quintet a more defined and dare we same glamorous shape. As the singer’s own time lapse photographs indicate, the surface makeover of a humble moss-color-haired chanteuse into bold blond bombshell is every bit indicative of the maturation and perfection of a band who has finally hit its stride.

If Grace Potter and the Nocturnals’ two formative Chicago shows in 2010 (Chicago Folk and Roots Fest, North Coast Festival) didn’t award them the keys to the city, surely the long-awaited, and sold-out, return to the House of Blues gave them their own zip code. Under the glare of crinkly metallic orbs and oddly positioned stuffed tiger heads, the band opened with track “Mastermind” (from 2007’s retort to Neil Young This Is Somewhere). Singing the chorus “One part sugar / Two parts feeling”, as she bounced from tambourine to piano to guitar, Potter offered a peek into her creative autobiography: a girl who can turn a sweet smile but has a laundry list of things to get off her chest. She sparkled like the stars, shimmied like a Supreme, and swayed like a flower girl in her white fringe dress that was just short of wings and a halo. And then “I declare this the Whisky A Go-Go”, brought her full circle to the rock show that hung in the bounds of the tiered House of Blues.

In true form “Tiny Light” displayed the epic stamina of the Nocturnals (guitarist/harmonica player Scott Tournet, drummer Matt Burr, bassist/backup vocalist Catherine Pepper, electric guitarist Benny Yurco) who, together volleyed in a blistering cagematch with Potter’s criminally evocative voice, created a rotunda of sound which was anything but tiny. It was psychedelic drama fitted with improvised jezebel jazz that took no prisoners in nearly four minutes. Thank goodness the show was sponsored by Jim Beam because there was no better excuse to take a shot than after that interlude.

Sadly the buzz was worn off quickly as a few songs later, Potter lost focus with the inclusion of her watered-down Kenny Chesney duet “You and Tequila” (Chesney’s part sung with Tournet) that offered nothing other than a few scratched heads. Clearly, Potter has enough chemistry alone that she needs no sparring partner and country’s genre-defining twang only subtracts from the reverent Stevie Nicks-Joplin-Grace Slick equation that makes Potter so damn charming.

For future shows, the band should skip the “Tequila” and rush right to the final numbers of the night — “Hot Summer Night” and “Paris (Ooh La La)” — which, along with Potter’s prowling dance moves, warranted the biggest cat calls of the show. A little bit country, a little bit rock ‘n’ roll may work for Donnie and Marie… but for Grace Potter and the Nocturnals, they should solely rock around the clock.