Bartoli,Fasolis, kammerorchesterbasel, Barbican, ***/ Gerhaher, Huber, Wigmore Hall, *****

Cecilia Bartoli always has a project, and her current one is to resurrect the work of Agostino Steffani (1654-1728) who combined the roles of spy, singer, bishop, and opera composer.

His attraction for her is partly that he’s been forgotten, and partly that his music reflects the transition between the Renaissance and the Baroque. At the Barbican we were warned she had ‘a slight cold’, but with the period-instrument kammerorchesterbasel working up a storm she swept gleefully onstage beating a tambourine in a voluminous turquoise ball-gown.

Her first aria called for Rome to be laid waste, and her mouth became a scatter-gun with each note aspirated at astonishing speed: these were the vocal gymnastics for which she is famed, but taken to a caricatured extreme.

Then – after a false start and a theatrical cough – she visited the opposite end of the spectrum as King Tassilone, dying with restrained dignity and supremely accomplished pianissimo control. Arias and instrumental interludes were strung together to create a kaleidoscope of moods, and to allow her to take periodic rests on her sofa while the orchestra serenaded her like an empress.

She duetted with an oboe, a theorbo, and a recorder, and had an anything-you-can-do duel with her trumpeter: circus stuff. But there were also bewitching moments as she and her band (athletically directed by Diego Fasolis) created nocturnal scenes, with Bartoli pretending – when she wasn’t laughing at her own virtuosity – to sing herself to sleep.

Bartoli may have a remarkable instrument, but gradually one became aware that something vital was missing even in her finely-sung Handel encore: soul.

She dazzles, but leaves the heart stone-cold. One couldn’t wish for a more telling contrast than that afforded by the German baritone Christian Gerhaher at the Wigmore Hall the following night, because with him every single note came from the heart.

He and his excellent pianist Gerold Huber had chosen a refreshingly unfamiliar selection of Schubert songs, where the connecting thread was stoical acceptance of sadness and loss: existential despair never came with a more lilting accompaniment.

Gerhaher’s artistry lies as much in what he doesn’t do as what he does, eschewing histrionics and letting each song come across as a series of thoughts which seem to have just struck him; his sound is not just beautiful, it’s the purest distillation of expressiveness.