"Richly expressive."

"Her rich, caramel-colored voice has portrayed everyone from poet Federico Garcia Lorca (in Osvaldo Golijov’s 2003 opera Ainadamar) to the naughty brother in Hansel and Gretel and much in between. Thursday she was in splendid form and “O that tellest good tidings to Zion,” gorgeously delivered, was one of the evening’s hold-your-breath moments."

“Kelley O’Connor’s Lucretia was the emotional center of the opera. Her poised mezzo shone, especially when singing of her longing for her husband, and in the convincing power of her lower register in her stern rebuff of Tarquinius’s advances. The quiet dignity with which she greeted Collatinus after her rape was devastating.”

"Enter mezzo-soprano Kelley O’Connor. Dressed in an elegant, sparkling gown that evoked the paintings of Klimt (Mahler’s contemporary in turn-of-the-century Vienna) O’Connor’s rich, dark-hued voice galvanized both the audience and the orchestra alike. Her first line is “O Man, take heed!” Everyone in the hall did. She articulated Nietzsche’s German text expertly and sang the plaintive passages with an artful modesty that called to mind former Vienna master Christa Ludwig."

“Mezzo-soprano Kelley O’Connor was wan and sensitive in ‘Der Einsame im Herbst,’ and her closing ‘Der Abschied’ was simply breathtaking, and mesmerising in its intensity. It showcased not only O’Connor’s remarkable richness and darkness of tone, but also her sheer range and suppleness of expression.”

"The most breathtaking moment arrived with the 'Urlicht' ('Primeval Light'), a solo for mezzo-soprano performed by O’Connor with exquisite control, expressive beauty and a voice of sheer gold."

“Kelley O’Connor’s brief appearance as Erda was something of a miracle. A natural stage presence, she walked on stage and all eyes were on her as she warned Wotan of the ring’s danger. O’Connor’s instrument is immense and imposing and she sang with a dark tone. O’Connor lengthened the line holding each note and emphasizing the text. It almost felt like there was no need to read the subtitles because her timbre expressed the foreboding destruction.”

“The matched set of concluding movements was inaugurated by a breathtakingly fine account of “Urlicht” by mezzo-soprano Kelley O’Connor, singing with ravishingly velvet vocal tone and an astonishing ability to sustain the song’s long, ardent phrases. Not since the late Lorraine Hunt Lieberson’s recorded performance with the orchestra in 2002 has this music been rendered with such physical presence or shimmery grace.”