BANGOR – The mark of a great concert is if you enter knowing little to nothing about the group performing and then leave wanting to head to the nearest music store to buy a CD or two and relive the experience over and over again.

It’s safe to say most novice or even casual Diamond Rio fans left the sweltering atmosphere of the Bangor Auditorium on a hot, humid Fourth of July evening wishing those local music stores were open so they could act on that impulse.

The country-western sextet wowed the 1,500 or so fans assembled on the floor and in the bleachers with a high-energy, 22-song, 82-minute set that showcased its unique blend of country music, showmanship and harmony as the musicians alternated between involving ballads and songs that simply made it impossible for even the most stodgy listeners to resist the temptation to tap their feet.

Baritone vocalist and bass guitarist Dana Williams remarked that Maine had hosted the group only twice in its 14-year career, and found it odd that the first time they ventured to Vacationland, it was so foggy at the harness track they were playing, he couldn’t see any fans past the first row.

“So this time around, we’re in Bangor, it’s 428 degrees outside, and we’re inside on the Fourth of July,” he said as the crowd laughed along with him.

It was fortunate the venue was inside, however, as another evening of thunderstorms made it wet and ominous beyond the Auditorium walls. As lightning cracked and thunder rolled outside, the bass boomed, the intensity flashed, and, in some instances, the ladies swooned as the Tennessee-based band delivered and then some. The highs were crisp and clear, the bass was clean and tight, and the vocals were distortion-free as the band started things off with “Meet in the Middle,” a No. 1 single from its debut album and ended with the raucous, toe-thumping “Unbelievable” before coming back out for a one-song encore from its forthcoming album, “Completely.”

The band’s signature style – catchy bluegrass harmonies fused with a driving beat and calming ballads, both accompanied by solid harmonization and instrumentals – was enough to beat the heat inside.

Members Marty Roe (lead vocals, guitar), Williams, Gene Johnson (tenor, electric mandolin), Brian Prout (drums), Dan Truman (piano, keyboards), and Jimmy Olander (lead guitar) seemed to be having a rocking good time as they interacted with each other and their audience with enthusiasm. Combined with a solid, 10-song set by opening act Allison Ames and the Flames, the evening provided plenty of flash and pop worthy of the Fourth.