Question:  "Amen" is a song featuring vocals by a duo consisting of who?
Context: "Amen" is a song by German musical project Enigma, featuring vocals by English dream-pop duo Aquilo.  It was released as the second single from Enigma's eighth studio album, "The Fall of a Rebel Angel" on November 18, 2016. Singer-songwriter Jonathan Clay grew up in Magnolia, Texas.  He released his first EP "Whole New Me" in 2006 on iTunes.  Atlantic Records signed Clay to a development deal in 2007.  In June 2007 Clay released his second album "Back to Good".  MTV music supervisors found his work on MySpace.  ABC Family used Clay's "After All" in "Lincoln Heights" in 2008.  Levi's and True Anthem sponsored Clay's give away of 140,000 downloads of "Acoustic Sessions" in 2008.  In 2010 Clay recorded "Everything She Wants" with producer Kevin Kadish.  "Gypsy Woman", a cut from that album, was used in the U.S. television series "Sons of Anarchy" in 2011.  In late 2010 Clay formed a new band called Jamestown Revival.  The duo teamed Clay with his childhood friend Zach Chance and within six months of forming the band the duo were featured in "Rolling Stone" magazine for the Cover of the Rolling Stone contest.  "Heart on Fire", a song featuring Clay's vocals, was featured in the 2012 comedy "LOL" starring Miley Cyrus, Demi Moore, Ashley Greene, Adam Sevani, and Douglas Booth.  Clay sang three additional songs for the film. "Déconnectés" is a 2014 single by French Moroccan DJ Hamida.  The single is taken from his mix series "À la bien mix party" with the song featuring vocals from Kayna Samet, Rim'K (of band 113) and Lartiste. The Ying Yang Twins are an Atlanta-based American hip hop duo consisting of Kaine (born Eric Jackson on December 16, 1978) and D-Roc (born Deongelo Holmes on February 23, 1979).  The group debuted in 2000 and rose to mainstream popularity in 2003 collaborating with Britney Spears on her "In the Zone" album and Lil Jon on "Get Low".  In 2004 and 2005, Ying Yang Twins became more popular with party singles "Salt Shaker", "What's Happnin", "Shake" and "Badd".  They have received notoriety for their song "Halftime (featuring Homebwoi)" which is played at New Orleans Saints homegames after most touchdowns.  In 2008, the hip hop duo released The Official Work mixtape.  In 2009, they followed with " their Ying Yang Forever mixtape.  Just three months later, the duo released Legendary Status: Ying Yang Twins Greatest Hits.  As recently as, 2013, the Ying Ying Twins released Ass in session and Twurk or Die mixtape.  The duo opened in December 18, 1997 and closed in July 24, 2014. "Galera" is a single by Jessy Matador.  The song featuring vocals from King Kuduro & Bra Zil; The original idea was born from the song titled "Galera" produced by the duo "BHB" Back Home Border Gianni Chiarparini & Nikholas Murphy; then the featuring with Jessy Matador that put his vocals on the instrumental beat.  After that the song was released on the August 1, 2011 in France and managed to peak to number 68 in the French Singles Chart.  It samples the 1978 disco hit "Let's All Chant" by Michael Zager Band. The Winstons were an American 1960s funk and soul music group, based in Washington, D.C., United States.  They are known for their 1969 recording of an EP featuring a song entitled "Color Him Father" on the A-side, and "Amen, Brother" on the B-side.  Half-way into "Amen, Brother", there is a drum solo (performed by G.C. Coleman) which would cause the EP to become the most widely sampled record in the history of electronic music.  Sampled audio clips of the drum solo became known as the Amen Break, which has been used in thousands of tracks in a large number of musical genres, including drum and bass, hip hop, jungle, big beat, industrial and electronica. "Bang Bang" is a song recorded by American producer and rapper will.i.am featuring the vocals of Shelby Spalione.  The single features as the third track on the of the 2013 Baz Luhrmann film "The Great Gatsby".  "Bang Bang" is also featured on the deluxe edition of will.i.am's fourth studio album "#willpower".  The song peaked within the top ten of the charts in Belgium (Wallonia) and the United Kingdom.  In the latter country, will.i.am is a coach on the country's version of The Voice and an alternate version of the song featuring vocals from Leah McFall ― the runner-up on season two of the show ― is included on the compilation "Now 86". "One Last Time" is a song recorded by American singer Ariana Grande for her second studio album "My Everything".  It was written by David Guetta, Savan Kotecha, Giorgio Tuinfort, Rami Yacoub, and Carl Falk.  The song was produced by the latter two, with Tuinfort serving as a co-producer and Ilya serving both as a co-producer and vocal producer.  "One Last Time" was first released on the iTunes Store on August 22, 2014 as the second promotional single from the album.  On February 10, 2015, the song was sent to contemporary hit radio as the fifth and final single from the album.  A French version of the song featuring French singer Kendji Girac, alternatively titled "Attends-moi", was released on February 16, 2015 in France, Belgium and Switzerland.  It is also included on the deluxe version of Girac's debut studio album "Kendji" (2015).  An Italian version of the song featuring Italian rapper Fedez was released on May 26, 2015 only in Italy. Tube & Berger is a deep house duo consisting of Arndt Rörig and Marco Vidoviz from Germany.  The duo is known in the United States for their 2004 number one Billboard Hot Dance Airplay song "Straight Ahead", featuring Chrissie Hynde on vocals. Aquilo is an alternative musical duo from Silverdale, Lancashire, England, consisting of Tom Higham and Ben Fletcher.  They began gaining recognition in 2013 for their singles such as "Calling Me" and "You There", in addition to their five EPs.
Answer: Tom Higham and Ben Fletcher