Joyce DiDonato concerts are never demure events. The question is how the addition of Antonio Pappano – and the overall air of a musical holiday – makes a difference. Over these two discs, music that needs special pleading certainly gets it, especially with the little-known composers of the first half, though the second disc of more popular repertoire threatens to run amok.

With its mixture of recitative and arioso, Haydn’s Arianna a Naxos scene can grow tedious. But DiDonato’s remarkable evolution as an actress now allows her to convey dramatic precision while respecting the music’s classical outlines. Where she might have pushed her voice harder in years past, she now seems to look more deeply into her vocal core for fine shades of emotion that catch the most minute change of mood. If there’s a single moment that illustrates DiDonato’s growth from an effective artist to one who achieves greatness, it’s the vocal decrescendo that suggests her lover’s ships fading into the horizon. Such things can be gimmicky, but here DiDonato conveys the cold slap of reality: he’s not coming back – an effect underscored by reverberent recorded sound that conveys just how alone Ariadne is.

The harmonic extravagance of I canti della Sera, a song-cycle by Francesco Santoliquido (1883-1971) that feels like theatrically astute Rachmaninov, shows how DiDonato and Pappano effectively cut away anything that’s interpretatively extraneous – in one of the few recordings anywhere of this once-acclaimed composer who fell into eclipse for his Fascist politics. The shamelessly lyrical Ernest de Curtis (1875-1937) could easily be cabaret music. But, as in the two Rossini trifles on the disc, the specificity of DiDonato’s conviction breaks through one’s preconceived notions about the respective genres.

Because these performances feel so right, the mis-steps in the second disc’s popular songs seem more obvious, suggesting that the diva is slumming it (even though she knows better). The first song group begins with a downright celestial version of Stephen Foster’s ‘Beautiful Dreamer’, arranged by David Krane with Impressionist chords suggesting Ives’s Central Park in the Dark. It’s also here that DiDonato’s voice has an expecially attractive plaintive quality, her small, quick vibrato recalling Frederica von Stade’s prime.

Elsewhere, in song choices that include rarities by Celine Dougherty and Heitor Villa-Lobos, DiDonato and Pappano are increasingly cavalier in ways that no doubt made the live event great fun but distract from the music’s content. DiDonato certainly has the voice to give ‘A Lazy Afternoon’ the understated eroticism of Kaye Ballard (in the original 1954 cast album of The Golden Apple on RCA Victor), but seems only able to pull back in time for her standard encore, ‘Over the Rainbow’, an irresistible talisman for this Kansas-born mezzo who, unlike her Wizard of Oz counterpart, will rule our emerald cities for years to come.