Less than a minute into last night's performance, it was obvious the members of the all-instrumental acoustic guitar duo Rodrigo y Gabriela (pictured right), Mexican natives now based in Ireland, care more about Metallica than Manitas de Plata. We can see why listeners mis-label their music as flamenco — it has a rhythmic precision and intensity that are also found in that style. After seeing all the headbanging and devil horns coming from the crowd, it's clear that their music has little to do with flamenco. We might go so far as to call Rod and Gab the first acoustic metal gods in rock n' roll history. This description of the duo's sound might make the music seem like a gimmick, but a gimmick will rarely deliver such a genuine and passionate performance, totally devoid of extraneous bells and whistles, while selling out the 9:30 Club. Rodrigo y Gabriela did both last night.

Rodrigo Sanchez and Gabriela Quintero work so well as a duo because they have similar musical influences, but at the same time they have disparate playing styles that are still complementary. He provides the melodies while she provides the rhythms. Rodrigo is the more traditional of the two guitarists and is also the more melodic. His playing is tasteful and technically sound, but also fairly orthodox. Gabriela, on the other hand, is the acoustic guitar's answer to a Tom Morello or Victor Wooten. Her percussive technique makes her more than just a rhythm guitarist as she not only plays the chord changes, but also transforms her instrument into a bass and drumset. While her playing is not as versatile as that of her bandmate, her approach is unique and she is the band's engine.

The depth of the group's musical influences, another reason behind their success, was apparent before they even set foot on stage. The opener, at Rod and Gab's request, was the impressive Alex Skolnick Trio. Skolnick, a member of the metal band, Testament, led his group through a strong set of tunes that ranged from guitar shredding metal to a straight-ahead jazz arrangement of Kiss' "Detroit Rock City."

Dressed in characteristic heavy metal black, and seated on stage with a screen showing live black and white images of the group's fretwork, Rodrigo y Gabriela tore through their 90-minute set. Their latest self-titled album was well-represented as they played through "Tamacun," "PPA," and several others, including their trademark arrangements of Led Zeppelin's "Stairway to Heaven" and the Metallica classic, "Orion." The Metallica influence was present throughout the performance as the group also performed "One" to open the encore, as well as snippets of "Enter Sandman" and "Sanitarium." The two also paid homage to other rock icons by quoting Deep Purple, Jimi Hendrix, and Rage Against the Machine. A highlight of the set was a special performance of Chick Corea's "Spain," which featured opener Skolnick as a guest.

Rodrigo y Gabriela, in addition to being fine musicians, are also one of those seemingly rare groups who dodge megalomania and pretention by going out of their way to establish a personal connection with the listener. Engaging in call and response, joking with the crowd, and even offering brief guitar lessons, the two musicians realize that an artist's most important asset is an understanding and appreciative audience. During one song, Rodrigo divided the audience into groups that clapped counterpuntal rhythms as the band performed one of its frenetic tunes. Because of this, Gabriela, in her endearing thick Mexican accent, declared us to be "fuckin' great clappers," an accolade if there ever was one. Another memorable moment saw the audience sing the entire lyric to Pink Floyd's "Wish You Were Here" as the band provided the musical accompaniment. Take that, all ye naysayers who think D.C. crowds are boring.

Photo from Rodrigo y Gabriela's MySpace page