Mozart, Wolfgang Amadeus: Symphonies No. 21-24 (PHILIPS 9500 888) and 36 ("Linz") and 39 (PHILIPS 9500 653). Academy of St. Martin-in-the-Field, Neville Marriner, conductor -- Ever since Marriner's box of the 31 early symphohies was released, people have been waiting for the second installment, which now begins. It now competes with the Joseph Krips records of the later symphonies, also on Philips. That cycle, with the Concertgebouw of Amsterdam, is a warm, rich, magnificent accomplishment -- some of the finest work the late maestro put to disk. Marriner is from a different school, and arguably, a different tradition, one that concentrates more obviously on form and beauty rather than mood and otherworldly vistas. His "Linz" is refreshingly free of ponderous overviews, of tuggings from beyond the shadows, yet full of reverence and sparkle when called for. If Krips is the model of a grand school now gone by (but still superbly valid) Marriner represents something new and just as convincing on its own terms. As always, the Philips sound and pressings are to ps in the commercial field today.