It may be the first time that the ensemble L’Arpeggiata, conducted by Christina Pluhar, accompanies a normal opera performance in a normal opera house. Although “normal” isn’t quite right, because “Belshazzar” by George Frideric Handel isn’t one at all Opera, but a high-baroque oratorio, which ultimately does not play a major role in the performance at the Theater an der Wien. On the other hand, the extraordinary musical quality of the evening plays a very important role. And that in a genre in which many outstanding special ensembles are active. What L’Arpeggiata and Pluhar are doing here is unique.