1964
“Gala Concert” included music by Stockhausen, Henze, Hindemith and others. Performers included Stockhausen, Neuhaus and Tudor, where Action Against Cultural Imperialism (AACI) protested], Solo Performance location: Town Hall NYC, 4/29/1964

The query describes an event on 
April 29, 1964, at Town Hall in NYC featuring a solo performance by Max Neuhaus, likely part of a larger concert. The concert program included composers like Stockhausen, Henze, and Hindemith, and performers such as Stockhausen and Tudor, notes a protest by the Action Against Cultural Imperialism (AACI).