Sorge's prelude to "Wenn meine Sünd mich kränken" is one of the 20 or something preludes by Sorge contained in manuscript Go.S. 597. Sorge's preludes in this collection are setup as a Trio. The chorale melody is accompanied by another voice and a bass voice. Some of them have an introduction with either one voice plus a bass voice, or two voices plus a bass voice. Sorge's prelude to the Lutheran hyms for passion tide "Wenn meine Sünd mich kränken" falls in the latter category.
The recording was done with the Hauptwerk software and the sample set, made by Voxus, of the Van Dam organ (1832) in Tholen (http://www.voxusorgans.com/en/tholen).
Score available here: http://partitura.org/index.php/georg-andreas-sorge-wenn-meine-sund-mich-kranken