Hey Ben,
What about "entermusic"? Bit naff? It's a bit difficult to come up with a funky/modern name and still incorporate the words music and entertainment. You could instead come up with a completely random word, that's not associated with either. As long as you get the marketing right, the name could be anything. It's all about building up a brand and it's association.
What type of music will be played at the festival and where? This could help you come up with a name. Do you have a website?
When are you planning to hold it? Sounds exciting - I might come and check it out