Johann Gottfried Walther wrote several chorale preludes to "Nun komm der Heiden Heiland". They are all of high quality. The one labeled (by Walther himself) 'Vers 2' has the cantus firmus in the pedal. In bar 7 and 8 the first notes of the choral melody appear in the alto voice as well. You need the score to see it, as it is difficult to hear.
The recording was done with the Hauptwerk software and the sampleset, made by Sonus Paradisi, of the Bader organ in the Walburgiskerk, Zutphen.
Score available here: http://partitura.org/index.php/johann-gottfried-walther-nun-komm-der-heiden-heiland-vers-2/