Soprano Christiane Karg, a wonderfully communicative singer, has chosen some of the finest of Gustav Mahler’s songs for this irresistible recording. The coup de théâtre here is that Mahler himself partners Karg on two songs, playing on a Welte-Mignon piano roll in 1905. The closing section of the Fourth Symphony (“Das himmlische Leben”) will give you goose bumps as two musicians perform together over a century apart. The excellent Malcolm Martineau plays the piano for the bulk of the songs, embracing the folksier Wunderhorn settings as well as the intense and great Rückert group, where Karg rises magnificently to the challenge.