One of Verdi's most melodic and exciting masterpieces, Un ballo in maschera (A Masked Ball) has returned to the Academy of Music after 19 years. It's definitely worth a visit; Robert Driver is to be congratulated on casting the five testing leading roles from — by today's standards, when Verdian voices are in short supply — considerable strength.

With admirably clean vocalism in Verdi's greatest tenor role, Marcus Haddock (as the governor of colonial Boston) alone captures the score's elegance. Angela Brown as yet lends little inner conviction to his beloved Amelia, but she sings much of her incredibly difficult part with impressive power and shine. Watch Gregg Baker's characterization as her husband (the governor's friend and adviser) come vividly to life when he thinks they've betrayed him: masterly acting. Renato's placement fundamentally suits Baker's imposing baritone less than some other roles he's aced here, but he provides some stirring moments. Young Sarah Coburn sparkles with bright confidence through the roulades of Oscar, the page. Barbara Dever commands the range and power for the fortune-teller Ulrica. And Curtis baritone James J. Kee makes a fine debut as the sailor Silvano.

Music director Corrado Rovaris has audibly improved OCP's orchestral standards, which tells in such instrumental details as the flute's voicing of Amelia's beautiful theme in Act Two's prelude and the lovely cello accompaniment to her later aria pleading to see her son. I've liked Rovaris' work in Verdi before, particularly in Santa Fe's Simon Boccanegra last year. But this Ballo, while capable, often seemed just too slowly paced; the slashing fire of Verdi's terrific ensembles goes missing. (This may improve as the run progresses.)

What Robert Driver is not to be congratulated on is his pedestrian staging: lacking insight into the potentially explosive interactions of passion, jealousy and vengeance that should define the leading trio; with minimal sense of period or place; and with the chorus (which sings well) arrayed in geometric groupings, as on a bus-and-truck tour. Boyd Ostroff's projections of 18th-century tarot cards hold the interest for about two scenes, then become intrusive, changing constantly and distracting attention from the action and music. Drew Biliau's lighting is aptly atmospheric, though the principals' faces are shaded far too often — including, alas, during the great Love Duet. The production's saving grace visually: Richard St. Clair's beautiful costumes, a fine start to his 20th season with OCP.

A Masked Ball Through Nov. 6, Opera Company of Philadelphia at the Academy of Music, Broad and Locust sts., 215-893-3600 or www.operaphilly.com