Choral- und Psalmvariationen. Par SWEELINCK JAN PIETERSZOON. With Volume 3 of Sweelinck's complete works for keyboard instruments, 'Chorale and Psalm Variations, ' editor Harald Vogel presents a group of works that can enhance many of today's religious services. Vogel's approach to the fundamental issues of performance practice in this edition is exceptionally knowledgeable. He begins by supplying…