The Metropolitan Opera never exercises restraint on important anniversaries. More is good. Too much is best. But the expansive nature of music director James Levine has rarely been so justified as in

James Levine: Celebrating 40 Years at the Met

- two boxed sets, one on video and another on audio drawn from radio and TV transmissions, each with 11 live operas.

The pricing is sensible and gift-friendly: $200 for the CD set, $300 for the DVDs at www.metoperashop.org or amazon.com. That averages out to $27 an opera. Performances show the greatest singers of our time - Teresa Stratas, Hildegard Behrens, Tatiana Troyanos, Lorraine Hunt Lieberson - in peak form not widely documented elsewhere.

In fact, the usual allowances made for archival performances aren't necessary here: Audio and visual elements are state-of-the-art, and casts are as meticulously handpicked as in well-considered studio recordings. Although the Met is criticized for conservative productions, what seems bland in the theater is often elegant and inviting on screen.

Levine's era began with the Met on the verge of financial collapse - as was the case with many New York City institutions in the 1970s. The Zeffirellian lavishness of the 1990s was a light-year off when an edgier, more austere Met cultivated a new identity in the 1979 telecast of the Brecht/Weill opera The Rise and Fall of the City of Mahagonny.

But the creation Levine made most his own, as time went on, is the orchestra: Although the ensemble's performance was iffy in the 1978 Bartered Bride, a 1980 Don Carlo telecast has much of its now-customary polish and effortless lyricism. By the 1998 Lohengrin, orchestra, chorus, and singers move as an amazing, single-minded force in a recording I'll return to often.

Repertoire choices reflect Levine's pet interests. Amid crowd-pleasers such as The Marriage of Figaro on DVD with Frederica von Stade and Kathleen Battle in a handsome if fussy Jean-Pierre Ponnelle production, the thorny operatic masterpieces of the Second Viennese School - Schoenberg's Moses und Aron plus Berg's Wozzeck and Lulu - are more than well represented.

The Berg operas each appear in two separate performances on CD and DVD. The CD Wozzeck has Anja Silja in terrible voice. The better-sung Wozzeck video reveals Mark Lamos' Fritz Lang-style production as one of the Met's most effective. The video 1980 Lulu has Julia Migenes stepping in - somewhat tentatively - for an indisposed Stratas, while the 2001 audio recording with Christine Schäfer shows the opera's dramaturgy so eloquently distilled, you hardly notice the music's atonality.

Repertoire holes are filled: Berlioz's rarely heard Benvenuto Cellini is welcome in any form, even with vocally miscast Marcello Giordani bullying his way through the title role. Harbison's The Great Gatsby with Lieberson, Susan Graham, and Dawn Upshaw grows on you upon repeated exposure. The Met's triple bill of one-act French pieces contains the single best recording of Ravel's L'Enfant et les Sortileges. How often do you hear an entire cast having so much fun?

Three Richard Strauss operas on DVD - Elektra, Der Rosenkavalier, and Ariadne auf Naxos - are all classics, though the 1994 Elektra reigns supreme: Behrens eclipses even her Wagner characterizations in this supremely challenging Strauss role and is equally matched by costars Deborah Voigt and Brigitte Fassbaender. Perhaps in response to its high audience walkout rate, Debussy's Pelleas and Melisande is conducted in broad strokes but with great casts (yes, plural, since the full recording, starring Jeannette Pilou, has bonus cuts of two other Melisandes: Stratas and von Stade).

The Levine Met is a great haven for divas. Levine cultivates them with a steady stream of roles that build their talent from season to season. Lieberson is featured in not just Gatsby, but also Berlioz's Les Troyens. Her Dido isn't the most comfortable vocal fit, but you want to hear it anyway. On DVD, mezzo-soprano Troyanos is seen in two of her signature roles - her comic Octavian in Der Rosenkavalier and the imperious Princess Eboli in Don Carlo - plus an aria concert with Plácido Domingo. Renata Scotto, whose reputation has been hurt by her having sung too long, shows why she earned that high reputation in the first place, in Don Carlo, and especially in all three leading soprano roles on a DVD of Puccini's Il Trittico. What a great, resourceful actress she was.

Her only match on that front was Stratas, who displays the theatrical depths of Vanessa Redgrave and the intense vocal characterization of Maria Callas. She blooms amid the confrontational social commentary of Mahagonny but is at her best in John Corigliano's The Ghosts of Versailles. Stratas plays one of the ghosts - Marie Antoinette - alongside a great cast, including a wildly comic Marilyn Horne and a young (and fleshy) Renée Fleming. In this sophisticated mélange of operatic manners, Mozartean and modern, centuries of opera come together - along with two generations of singers. It's the grandest of operas. If anyone ever wonders what was great about the Levine era, this video has it all.

Contact music critic David Patrick Stearns at dstearns@phillynews.com.