This is EMI's curent remastering of Klemperer's classic B minor Mass from 1967. Along with Klemperer's St. Matthew Passion, this recording was the summit of what he could do in Bach. The vocal soloists are wonderful, especially the women led by Janet Baker. In retrospect these were the best Bach singers in Europe, and the ones we hear on period performances from Gardiner and Herrenweghe, among others, are inferior by comparison. Over and over we now get accomplished vocal technicians without spiritual involvement in Bach's passionate Protestantism (blessed exceptions being Lorraine Hunt Lieberson and Thomas Quasthoff).
The Philharmonia Chorus, trained by the legendary Wilhelm Pitz (who also led the Bayreuth Festival chorus) at this time was probably the best in the world. Klemperer's tempos are stately but full of life in their inward way, and the overall experience fills one with Bach's sense of joyful worship.
P.S. 2011 -- For anyone who is of an age or inclination to enjoy such old-fashioned grandeur and reverence in Bach, there are two other stereo versions of the B minor Mass that are pendants to this one. The first, under Karajan, dates from the same period of mid-Sixties and is distinctly more polished -- some might say overly polished -- with equally prominent opera singers as soloists. There are drawbacks to the sound on both the Klemperer and Karajan, the large choruses being particularly fuzzy, so there's little to choose between them. For a huge cathedral sound coupled with superb musicality, there is a live account under Giulini, taped by the BBC in 1972 (on BBC Legends). It is gentler than either of its rivals, and although live, the performance is of studio quality. One glitch may be the vast space of St. Paul's Cathedral, where the reverberation time is several seconds more than any concert hall, but the engineers have done a good job handling that.