Audio data having M channels includes a header with metadata specifying a conversion function for converting the M channels of digital audio data into N channels of data. The at least two lenses are arranged sequentially in a beam path, where the at least two lenses are made from a material that is stable when exposed to laser radiation having a power of more than 1 kW, and at least one of the lenses has at least one aspherical lens surface. 5 and 3 equivalents calculated with respect to the amount of silyl-protected alkynol ester with formula.