Tina Korhonen / submitted photoClassical guitar duo Rodrigo y Gabriela -- from left, Gabriela Quintero and Rodrigo Sánchez -- are getting ready to record their fifth studio album, the follow-up to 2014s stripped down "9 Dead Alive." They will perform at the Athletic Club of Bend tonight.

Rodrigo Sánchez and Gabriela Quintero, aka classical guitar duo Rodrigo y Gabriela, have always sought to push their music in new directions.

The Mexican metalheads started their career in Europe in the early 2000s, playing favorite songs from bands such as Metallica and Led Zeppelin in a nuevo flamenco style. Their first three albums reflected both influences, featuring armies of acoustic guitar overdubs and guests on piano, violin and electric guitar. On 2012’s “Area 52,” the duo blew up their sound, recording with Cuban orchestra C.U.B.A. And on 2014’s concept album “9 Dead Alive,” the two stripped back down to a duo, creating perhaps the most accurate recorded reflection of their energetic live shows (save for their multiple live albums, of course).

For their next album, the instrumental duo will once again try something different — vocals. And although the band collaborated with Øystein Greni, lead vocalist of Norwegian rock band BigBang, on a cover of Spirit’s “Nature’s Way” in 2015, the new songs are unlike anything the duo have done before.

“What we’re doing for this album is — I mean, in terms of vocals, it’s not covers,” Sánchez said recently from Ixtapa-Zihuatanejo, Mexico, where he and Quintero were recording demos before heading out on a West Coast tour that kicks off tonight at the Athletic Club of Bend.

“We’ll be releasing our songs. It’s quite different. Where normally we come from where we come — musically speaking, from kind of metal. I’m not saying it’s a metal song, but it’s much more rock than ‘Nature’s Way’ or (our) kind of usual writing style.”

To hear Sánchez tell it, what’s on deck may be the most eclectic material of the duo’s career, with throwbacks to almost everything they have tackled before along with new surprises.

“We have some guests that come from different genres of music, and fans would probably know (if) they follow what we’ve been doing and who our regular guests — they will probably guess who they are,” he said. “… And the regular Rod and Gab tracks, and some — three metal covers, full on, like the way we did it with (Metallica’s) ‘Orion’ on the first album (2006’s ‘Rodrigo y Gabriela’), but different. It’s going to be very eclectic, but I think the main addition, of course, will be vocals in three tracks.”

The duo plan to hit the studio once the current tour wraps in Solana Beach, California, on Aug. 16.

“We are kind of 30 percent into the album,” Sánchez said. “… We’re gonna spend a lot of the following months between (tours) recording and see if hopefully by the end of the year, it’s ready to be released next year, obviously.”

These days Sánchez still calls Ireland home. He and Quintero landed in Dublin at the turn of the century after trying their hand at more traditional metal in Mexico. Since finding their voice as an acoustic duo, the two have performed for President Barack Obama at the White House in 2010, composed music with Hans Zimmer for 2011’s “Pirates of the Caribbean: On Stranger Tides” and made the rounds on late-night talk shows.

As the duo’s star rises, the venues get bigger — this tour includes a stop at the Hollywood Bowl. Needless to say, it can be quite a challenge for two nylon-string guitar players to come across in arenas.

“We kind of developed a good way to make acoustic guitars sound quite big, but it’s a lot to do with the guitars we play as well — we’ve been working with Yamaha guitars,” Sánchez said. “… And we have developed a very good sound, and understanding that we were kind of the first band playing that kind of (music), especially on (nylon-string) guitar and that kind of rhythm for big situations, not only for small clubs. … We knew that we needed a system that just wasn’t there back in the day.”

In the studio, of course, they can overdub guitar tracks. Their metal background has come in handy not just for material, but recording techniques as well — especially on the aforementioned cover of “Orion.”

“When I was a kid, I used to read a lot of interviews about the way especially Metallica would record the albums, having James (Hetfield, lead vocalist and guitarist) recording like four to five guitars,” Sánchez said. “My metal bands, we used to do the same. And then years later we met Metallica, and I asked James why, (he said) he thought that was a good idea because (he could get) pretty … powerful guitars. You know, he had his own ideas about it, but they stopped doing that years later. But for us, having those two guitars, it was essential to overdub to make that sound fatter.”

The duo went the opposite direction for “9 Dead Alive,” an intimate recording that sounds like Sánchez and Quintero playing in a room together, facing each other (which Sánchez said was indeed the case).

This recording and composing technique grew out of the concept behind the album. Each of the nine compositions on the album pays tribute to an important historical figure, including Austrian neurologist and Holocaust survivor Viktor Frankl (“Sunday Neurosis”), Chilean poet Gabriela Mistral (“Megalopolis”) and famed abolitionist Harriet Tubman (“Misty Moses”).

“I think it was just, we wanted to come up with something more about — apart from the actual music side of it, we wanted to make a contribution in kind of a more cultural way,” Sánchez said. “That’s why we picked people that (are) not the usual suspects. We didn’t want to pick Gandhi or Martin Luther King (Jr.), because people know about them, or they should at least. We wanted to introduce people who were not as popular or famous as these ones, but they were just as great.”