((Reference for a preliminary ruling from the Bundesgerichtshof – Interpretation of Article 13A(1)(n) of the Sixth Council Directive 77/388/EEC of 17 May 1977 on the harmonisation of the laws of the Member States on turnover taxes – Common system of valued added tax: uniform basis of assessment – Other cultural bodies recognised by the Member State concerned – Soloist (included thereunder?) – Activities in the public interest – Concert with primarily commercial aims (included thereunder?)))