So when Andreas Scholl started clearing his throat between song verses, the disjunction between soprano-register singing voice and manly throat tones felt jolting, like catching awkward glimpses of the mechanics behind a fragile mask.
But then, this recital was all about expressive vulnerability. Scholl was performing with his wife, Israeli pianist Tamar Halperin, and the musical intimacy between them was unguarded and touching.
She played solo piano interludes - unusual for a song recital and a lovely gesture - of Schubert (a little B-minor waltz, D145), Mozart (Rondo in F, K494) and Brahms's tender Intermezzo in A, Op 118 no 2.
She isn't the most refined pianist, but she brought a candid improvisational quality that added to the sense that everything in this recital came from the heart.
Scholl's voice has lost the pure and luminous sheen it once had, and there were only flashes - in three of Haydn's Original Canzonettas - of his great operatic resonance.
It was in his soft low notes that he sounded most communicative; these were ravishing in Schubert's Du bist die Ruh and Brahms's In stiller Nacht. In Schubert's Death and the Maiden he even broke into tenor voice to sing Death's lines - a chilling effect.
The programme ran continuously between songs, carefully planned to make coherent thematic and musical lines. The encore was a syrupy number written for the couple by Israeli pop star Idan Raichel, using the same German folk text as Brahms's In stiller Nacht. Another thoughtful touch.