BUDAPEST — Fans rushed the stage as the first chords of “You Shook Me All Night Long” rang out in the Laszlo Papp Budapest Sports Arena last October. Young women in tight miniskirts and boots whipped their hair at the musicians while denim-clad young men, their fists pumping the air, shouted out the lyrics to the 1980 hit by AC/DC.
As the sellout crowd of 6,000 exulted, the performers kicked it up a notch. Luka Sulic and Stjepan Hauser made the crowd roar and scream by playing instrumental covers of songs by U2, Michael Jackson and Nirvana.Katja Kinnunen, who came from Finland to see the show, said she was not disappointed, having seen videos of the group on YouTube, where their arrangement of AC/DC’s “Thunderstruck” has had over 59 million views.
“If you play with passion, that’s my thing,” she said. “They blew my mind.”
Pretty typical commentary for a rock concert. But this was not a tribute show by an ’80s imitation band. The musicians are two classically trained Croatian cellists who perform as 2Cellos, and their genre is instrumental classical crossover — a small but surging subset of classical and pop music.
“We want to show the possibilities of cello playing,” Mr. Sulic said before the show. “To break the boundaries between different genres of music.”
Mr. Hauser laughed and put it more bluntly: “I wanted to have screaming girls in the audience, which we get now for sure.”
That two classical musicians could get a Hungarian crowd out and screaming on a wet autumn night is a testament not only to 2Cellos — who count Elton John, Quincy Jones and members of Iron Maiden as their fans — but also to the growing popularity of instrumental classical crossover. Thanks to social media and easily accessible music download sites like Spotify and Apple Music, musicians like the Piano Guys from the United States, Apocalyptica of Finland, the Australian/British violin quartet Bond, and Maksim Mrvica, a Croatian pianist, have found fans across the globe interested in listening to instruments usually reserved for symphony halls.
While the number of instrumental classical crossover artists seems to be growing, it’s not a new phenomenon. As far back as the 1940s and 1950s, classically trained opera singers like Mario Lanza and Eileen Farrell were recording popular songs. The Pulitzer Prize-winning music critic Lloyd Schwartz, who writes for publications including New York Arts and The Berkshire Review, dates instrumental classical crossover to 1985, when the Kronos Quartet recorded the Jimi Hendrix hit “Purple Haze.”
“That was eye-opening,” Mr. Schwartz said. “It also suddenly made you take Jimi Hendrix, in a way, more seriously, though he was obviously idolized. But there was real music there, so people who loved classical music were, “Oh well, this is really exciting music.”’
Meanwhile, many classical crossover musicians hope their music can serve as a gateway to get younger audiences interested in classical music. “We try to make a revolution, not only with cello playing but also classical music,” said Mr. Sulic, 28, who holds a master’s degree from the Royal Academy of Music, in London. “Presenting it to a younger generation, in a different light, showing how cool it can be.”
“The longtime internal debate within the classical music industry was about whether or not crossover was going to help the sales, visibility, and commercial viability of core classical music,” she wrote in an email. “The argument went this way: if a fan liked 2Cellos or Bond, for example, s/he would hopefully find her/his way into listening to “serious” classical artists and composers. That didn’t ever happen; instead, the audience’s hunger for crossover music was sated by more crossover artists, and more releases from crossover stars.”
What instrumental classical crossover has surely done, though, is opened up the possibilities for classically trained musicians to find homes in a variety of spaces, from orchestra halls to underground clubs. “Musical talents are, thankfully, no longer restricted by conventional notions of ‘classical,’ ‘rock,’ ‘pop’ and so on,” Jonathan Freeman-Attwood, the Royal Academy of Music’s principal, wrote in an email. “There’s still a prevailing sense that musicians who’ve had a ‘classical training’ are somehow expected to live in a little elite box.
“If you knew what they were listening to as they rolled up to a Shostakovich rehearsal with a great conductor, you’d be surprised,” Mr. Freeman-Attwood said. “And it’s not necessarily Shostakovich.”
Bands like the cello metal group Apocalyptica were certainly listening to more than just the classical composers when the three cellists (a fourth plays drums) were studying music at the Sibelius Academy in Helsinki in the early 1990s. This year marks the 20th anniversary of the release of their first album “Plays Metallica by Four Cellos.” The band, in the midst of a worldwide tour to support its latest release, “Shadowmaker,” have opened for Metallica 10 times and recorded with Sepultura on their 2001 album “Nation.”
Eicca Toppinen, a member of Apocalypta, said that when they started out, there were not many artists who were seriously combining music styles but that nowadays “there seem to be tons of artists and projects” that fall into the classical crossover category. “I think the big reason for that is the pioneers showed people that you can play different styles with different instruments,” he wrote in an email, “and that encouraged many young classical players to feel more free with what they wanted to play.”
There are, of course, detractors who say that classical crossover muddies the waters. The British baritone Thomas Allen stated in 2002 at the Royal Philharmonic Society Awards that “money-grabbing, P.R.-led” marketers were using “wet T-shirted” violinists to sell classical music. “And I’m sick and tired of hearing of those performers who talk of it as their life’s work to bring culture and the classics to a wider public as though they are a band of nursing sisters seeking to restore a terminally-ill patient,” he continued.
Steven Sharp Nelson, who plays cello for the Piano Guys, disagreed with Mr. Allen’s critique. “I think that is being über-judgmental to say that all classical crossover is money-grabbing,” he said by telephone. “Maybe some of it is, but I think there is a true desire out there on a lot of classical musicians’ parts to explore, discover and to innovate just like the composers of old did, and to touch people who would normally not step foot inside a classical music hall.”
There is, of course, money to be made, but do all the YouTube and social media followers translate into album and concert sales? Mr. Nelson thinks so; the Piano Guys has over 4.5 million subscribers on its YouTube channel and recently performed to sell-out crowds in New York, at Carnegie Hall, and in Denver, at the Red Rocks Amphitheater.
“We still sell more physical albums than we do digital,” he said, “but we see a trend in our music to all digital.”
Mr. Freeman-Atwood agreed. “I have no doubt that the next generation of musicians will come up with many more new ways to share their talents with the world,” he wrote. “Which is not to say the traditional approach is no longer valid. Music is a broad church and it is becoming broader with every year.”