ASPEN — If Jazz Aspen Snowmass’ June Festival, held this past weekend in Aspen’s Rio Grande Park, were a competition between musical styles, it was no contest. In terms of artistic satisfaction, cool factor and, especially, instrumental daring, the jazz faction won out big over the rock ‘n’ rollers.

The performance of the weekend, by a large margin, was turned in by Dianne Reeves, Thursday night’s headliner. The fact that a singer of straight-ahead jazz could make a big enough sound to reach the back of the tent probably didn’t come as a surprise; the Denver-based Reeves showed the power of her voice in a June Festival appearance three years ago. What was stunning, and brilliant, about Reeves’ performance was that she was accompanied by nothing more than two guitarists, played by Russell Malone and the Brazilian-born Romero Lubambo.

So that’s two guitars, neither of which were turned up anywhere near loud, and one voice, delivered by a woman sitting in a chair. That’s the formula for an intimate little jam session — not a tent that can accommodate nearly 3,000 people. But the exchange of musical ideas between Reeves and her two sidemen was profound — big enough to reach the far corners of the tent, and precise and soulful enough to stir the souls of anyone listening closely. Little wonder that George Clooney used Reeves not only on the soundtrack of his stylish 2005 film “Good Night, and Good Luck,” but also as an on-screen presence.

Reeves has toured with her spare, two-guitar arrangement through Europe, but this was only the second U.S. performance for the trio.

Matching Reeves for brashness in instrumental configuration was Christian McBride. The bassist, and artistic director of Jazz Aspen’s JAS Academy educational program, appeared in the opening slot on Sunday evening in what he terms “A Christian McBride Situation.” This particular “Situation” featured two turntablists — DJ Logic and Jahi Sundance — keyboardist Patrice Rushen, saxophonist Walter Smith III and vocalist Maysa Leak — in other words, a groove show without a drummer. But with McBride front-and-center, alternating on acoustic and electric basses, and the DJs providing the beats, the set lacked little in the rhythm department.

What the performance could have used more of was rehearsal. It was, in fact, the first Situation with two DJs, as well as the first with a vocalist. And while the sextet had no trouble falling into fat, funky grooves, they could have used a few practiced songs to give the show more variation and texture. Leak, a talented singer and compelling presence, had to resort to wordless scat singing too often.

The two big rock-oriented shows could have used more of that improvisational spirit. Both the Brian Setzer Orchestra, which headlined Saturday night, and Los Lonely Boys, who closed the festival Sunday night, played tight, high-energy, crowd-pleasing shows. But both fell into their separate predictable patterns, with barely a surprising moment to be found.

In their local debut, the 18-piece Setzer Orchestra, led by the former singer-guitarist of the Stray Cats, stuck close to the rockabilly-swing formula. At one point, Setzer played a bit of Mozart’s familiar “Eine Kleine Nachtmusik” to a rockabilly beat — his idea of changing things up. Los Lonely Boys, a Tex-Mex trio making its second Jazz Aspen appearance in three years, likewise showed energy and talent — but little inclination to step close to the artistic edge. Their sound mixed Stevie Ray Vaughan-inspired blues-rock with Santana-esque Latin touches, and while Henry Garza is a guitarist worthy of exploring such territory, there was a shortage of innovation.

The disappointment of the festival was singer Bebel Gilberto. The daughter of bossa nova pioneer João Gilberto offered a monotonous take on the Brazilian style, while trying to convince the audience otherwise with a series of dramatic movements of her arms and head.

Far more convincing was Sharon Jones. Akin to a female version of James Brown, Jones resurrected old-school soul with intensity and drama, and distinguished herself with fine original songs like “100 Days, 100 Nights” and “How Do I Let a Good Man Down?” While Jones never went overboard with the retro aspect of her act — she never once tried a move associated with the late Godfather of Soul, Brown — she could have broken with tradition and given her excellent band, the Dap-Kings, a little longer leash to explore their instruments.

When it came to filling seats, neither the jazz nor the rock artists did a bang-up job. Overall attendance barely topped 8,000 over four nights, a substantial drop-off from last year, when such relatively big names as jazzman Herbie Hancock (accompanied by friends including Keb’ Mo’) and rockers Steve Winwood and the Black Crowes drew a record attendance of more than 11,000 over four nights. The highest turnout this year came Friday night, when vocal group the Manhattan Transfer and r&b singer Anita Baker drew some 2,400 fans.

stewart@aspentimes.com