The German soprano Angela Denoke is giving a first-rate performance as the Marschallin in Rosenkavalier at the Met. Any New Yorker who loves Strauss' sixteen-ton comedy, or who wants to experience the ultimate artistic meditation on the self-absorbed minitragedies of thirtysomethings, should try to see it. Denoke sings with phenomenal purity of tone, yet she is also an emotionally transparent, actorly performer; there's a welcome lack of expert caution in her delivery, and an expressive dark lining to even her brightest upper notes. Last night, Kristine Jepson was an excellent, athletic Oktavian; the appealing Laura Aikin had maybe a bit of an off night as Sophie (constricted in the early part of Act II); Peter Rose cut a likeable, consistently funny figure as Ochs, enlivening parts of the opera that can otherwise drag (as it were). Donald Runnicles avoided the over-refulgent, singer-swamping sound that has marred some of James Levine's performances of this work; in all, it was a luminous, fleet-footed night. Ja, ja!