The full fury of a great Verdi opera is not often felt, and when it is, you'd rather be in a larger room than the Helen Corning Warden Theater at the Academy of Vocal Arts' Spruce Street headquarters.

Nonetheless, there we all were on Tuesday at Un Ballo in Maschera, shoehorned into those airplane-size seats, so spellbound that we might as well have been hostages, with conductor Christofer Macatsoris zapping a consistently fine cast with what seemed like electric shocks in a tale of revenge that stops at nothing.

You know it's working when somebody sings "Night of horror!" without sounding melodramatic. Because you agree.

The opera's ingredients include a less-than-beloved monarch, an assassination, a den of witches, and small children used as bargaining chips, with music that magnifies everything in a way only opera can. When infidelity is discovered between King Gustavo and his best friend's wife, you felt not a theatrical device, but the depth of sorrow at the lives being ruined.

The Tito Capobianco production was handsome and functional - the masked ball had a diagonally slanted overhead mirror implying depth of field - and allowed the opera to pour off the stage with no filter of artifice.

Though not all singers seemed ready to sing their roles in big-theater circumstances, they easily filled the small one. Marina Costa-Jackson (Amelia) needed to float more high notes and not push so hard - but what rich tone. Tenor William Davenport (Gustavo) had great vocal ease and precision. His nemesis was sung by Zachary Nelson, who may be a true Verdi baritone, equally capable of tenderness and rage. Shelley Jackson was an unusually charming Oscar.

Evil doesn't come easily to mezzo-soprano Margaret Mezzacappa, who played the witch Ulrica, seized by visions and taking subtle delight in the bad fortune in store for those who look down on her. But when her second sight grew dark with visions that would change history, she projected overwhelmed terror. Her vocal approach was essentially lyrical, with a deliberate articulation of the text telegraphing the character's higher perception.

As for Macatsoris, nobody conducts better Verdi, partly because he embraces the music's vulgarity with explosive deployment of percussion, fast tempos, and a way of making rhythm feel implacable, even though in more reflective passages he molds his phrase to whomever is singing with endless elasticity.

Additional performances (double cast): 7:30 p.m. Thursday and Saturday at the Helen Corning Warden Theater at the Academy of Vocal Arts; 7:30 p.m. Wednesday in Centennial Hall, Haverford; and 7:30 p.m. May 11 at Central Bucks South High School in Warrington. Information: 215-735-1685 or www.avaopera.org

Contact David Patrick Stearns at dstearns@phillynews.com.