They made about 200 recordings . They were especially known for playing quartets by the great classical composers Mozart , Beethoven , Schubert and Brahms , but they also played works by 20th-century composers such as BartÃ k and Benjamin Britten ( who wrote his third quartet for them ) . The Amadeus Quartet made some 200 recordings , among them the complete quartets of Beethoven , Brahms , and Mozart and works by 20th-century composers such as BÃ la BartÃ k and Benjamin Britten ( who wrote his third quartet for them ) .