Quasthoff was both demanding and extremely playful. His masterclass was a performance for the audience to enjoy: he was quippy, and quite charming (hearing him sing portions of the pieces prepared by the four students was another perk). I can only imagine that the prospect of singing German Lieder for one of the reigning champions of the style was as daunting as it was exciting, but the students and masterteachers were able to create some very distinct changes in interpretation.
Based on his own performing style, it was not a surprise to me to hear how much importance Quasthoff puts on the emotional content of the songs. But it was wonderful to hear this approach repeatedly emphasized nonetheless. In the day-to-day routine of conservatory life, as we strive so much to become the most proficient, clean singers we can be, it's easy to lose focus of what actually matters in a performance. Yes - a proper technique is important, but only as a means to a heartfelt interpretation. Over and over, Quasthoff underscored the importance of feeling and living the music as a human rather than a singing machine - pronouncing the text clearly but naturally, imbuing both the piano and vocal lines with a sense of atmosphere, progressing emotionally, using one's imagination, etc... His other repeated concern, that the performers use their entire bodies to create sound, goes hand in hand with the first motif of his lesson. The bottom line is that singers and pianists (and any other instrumentalist as well) must be people above technicians. They must use their entire selves, the outside and the inside, in order to express the notes. They must live, and create for the audience performances informed by their life experiences. Without this full dedication to and sense for the music, they are not creating art at all, but merely a series of audible frequencies of varying lengths.