Mendelssohn's string quartets belie the received image of his being an emotionally safe composer, and the Quatuor Ebène's latest album presents us with what are probably the most intense pieces in his output. The Second and Sixth Quartets are both works of mourning: the former (1832) is a profound memorial to Beethoven; the traumatic Sixth (1847) records Mendelssohn's reaction to the death of his sister Fanny, whose own String Quartet in E flat is placed alongside her brother's masterpieces. Written for private performance at her Berlin salon, it has a formal daring that Felix, very much in the public eye, was never quite in a position to emulate. The Ebènes probe all three works with unflinching honesty and immediacy that don't make for easy listening, but are unforgettable.