Electric guitars are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Electric guitars are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

The body of an electric guitar is displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Electric guitars are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Electric guitars are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

The headstock and tuners of a Fender guitar is seen inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Music pedals are displayed for sale inside the vintage guitar sshop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

The bridge, the volume and the tune bottom are seen on the body of an electric guitar as it is displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Music pedals are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Electric guitars and Thermion amplifiers are displayed for sale inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

The headstock and tuners of a Gibson guitar is seen inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Headstocks and tuners of acoustic guitars are seen inside the vintage guitars shop "Headbanger" in central Madrid, Spain, April 4, 2018. REUTERS/Sergio Perez 

Pedro Gonzalez attends a guitar class at the private music school Escuela de Musica Creativa in central Madrid, Spain, November 6, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken November 6. REUTERS/Andrea Comas 

Pedro Gonzalez poses with a guitar outside a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas TPX IMAGES OF THE DAY

Pedro Gonzalez plays guitar inside a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas 

Pedro Gonzalez plays guitar inside a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas 

Pedro Gonzalez smiles during an interview inside a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas 

Pedro Gonzalez plays guitar inside a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas 

Pedro Gonzalez (R) plays a guitar next to his teacher Joaquin Chacon during a guitar class at the private music school Escuela de Musica Creativa in central Madrid, Spain, November 6, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken November 6. REUTERS/Andrea Comas 

Pedro Gonzalez looks through a window into a guitar store in central Madrid, Spain, July 24, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken July 24. REUTERS/Andrea Comas 

Pedro Gonzalez is reflected in a mirror during a guitar class at the private music school Escuela de Musica Creativa in central Madrid, Spain, November 6, 2015. If you're a guitar aficionado visiting the Headbanger Rare Guitar shop in Madrid, Spain, you're likely to find a teenager in a baseball cap bent over a 1955 Gibson, his nimble fingers producing jazz scales rarely heard from a mere 17-year-old. The enticing shop, with a selection of vintage guitars hanging from black walls, is a second home to Pedro Gonzalez, who is attracting attention in the Spanish capital for his talent playing jazz guitar. Picture taken November 6. REUTERS/Andrea Comas 

Heavy metal fans headbang during heavy rainfalls at the 24th Wacken Open Air Festival 2013 in Wacken, August 3, 2013. More than 75, 000 heavy metal fans visited the largest heavy metal festival in the world. REUTERS/Fabian Bimmer (GERMANY - Tags: SOCIETY) 

Heavy metal fans headbang during heavy rainfalls at the 24th Wacken Open Air Festival 2013 in Wacken, August 3, 2013. More than 75, 000 heavy metal fans visited the largest heavy metal festival in the world. REUTERS/Fabian Bimmer (GERMANY - Tags: SOCIETY) 

A fan headbangs during a concert at the 24th Wacken Open Air Festival 2013 in Wacken, August 2, 2013. More than 75, 000 heavy metal fans visited the largest heavy metal festival in the world. REUTERS/Fabian Bimmer (GERMANY - Tags: SOCIETY) 

Actor William Shatner accepts The Honorary Headbanger award at the 3rd annual Golden Gods awards in Los Angeles April 20, 2011. REUTERS/Mario Anzuoni (UNITED STATES - Tags: ENTERTAINMENT) 

Actor William Shatner accepts The Honorary Headbanger award at the 3rd annual Golden Gods awards in Los Angeles April 20, 2011. REUTERS/Mario Anzuoni (UNITED STATES - Tags: ENTERTAINMENT) 

Fans of the band Motorhead shake their heads during their performance at the 35th Paleo music festival in Nyon July 20, 2010. REUTERS/Denis Balibouse (SWITZERLAND - Tags: ENTERTAINMENT IMAGES OF THE DAY SOCIETY) 

Actor Robert Englund (L) hugs presenter Kat Von D as he accepts the Honorary Headbanger award at the 2nd annual Golden Gods awards in Los Angeles April 8, 2010. REUTERS/Mario Anzuoni (UNITED STATES - Tags: ENTERTAINMENT IMAGES OF THE DAY) 

Actor Robert Englund accepts the Honorary Headbanger award at the 2nd annual Golden Gods awards in Los Angeles April 8, 2010. REUTERS/Mario Anzuoni (UNITED STATES - Tags: ENTERTAINMENT) 

Revellers gestures during the concert of rock band Motorhead at the 41st Montreux Jazz Festival July 7, 2007. REUTERS/Denis Balibouse (SWITZERLAND) 

Jonathan Davis, lead singer of American nu-metal rock group Korn, performs during the Metalway Festival in Gernika, northern Spain, August 13, 2005. Fifteen thousand fans gathered in the Spanish basque town for three days of heavy metal music, from groups such as Accept, Saxon and W.A.S.P. REUTERS/ Vincent West Pictures of the Month August 2005 VPW/SV/PN