The Bach Mass in B minor, BWV 232, assembled from bits and pieces over some years, coheres in its final form in ways that perhaps only the composer understood. This recording by the Choir of Trinity College Cambridge and Orchestra of the Age of Enlightenment under Stephen Layton has been road-tested in performances around Britain for several years, but it hasn't lost the enthusiasm of its youthful singers. With a choir of 40+, it's not a recording for the historical-performance crowd, but it's musical, filled with clear, bright contrasts, and really quite grand. Layton takes a deliberate approach to the score, catching its long lines and letting the choir swell and surprise when they want to. The contrasts also involve the soloists, a varied bunch of well-known names that keep things exciting. The bloomy voice of soprano Katherine Watson might or might not be to your taste, but it plays well off the others. Sample the slow polyphony of the final Dona nobis pacem for a taste of the choir's Romantic approach, which one suspects wouldn't have sounded too unfamiliar to Mendelssohn. Whatever your own verdict, the support the singers get from Hyperion engineer David Hinitt and producer Adrian Peacock, working at the Trinity College Chapel, is superb: In a difficult situation, the various sound groups are kept clear, and there's not a trace of mush.