Bernard Levin talks to the four members of the Amadeus Quartet and they play Schubert's Quartet Movement in c minor. In 250 years of quartet playing, no group of musicians has stayed together as long as the Amadeus Quartet. They are about to celebrate their 35th year of playing, teaching and making records all over the world. If one player had to stop for any reason, they would all stop, for, as second violinist Siegmund Nissel says, ' I could not contemplate playing quartets with someone else'.