Sci Fantasy story published 1950s - 1970s about about aliens who take over humans. Looking for title / author please

I am trying to hunt down this story for my boss (one of two stories he has me hunting). He can remember the plot but has no idea re: author or title.

Apparently in the story aliens take over humans by having them perform music or artistic works. One human then shoots all the aliens in his quest to be a hero (even though the aliens were having the humans produce beauty and art instead of destroying them).

Any help or suggestions greatly appreciated thanks.