This happens in the music biz everyday. Trademarking sucks, look at kiss. Whats his name the singer trademarks 10 things a day for sport. Anything with kiss on it he owns. Make a play, they may want the website for bucks, or they do the old c&d. You mentioned grammy winner, well the artist are pretty stupid when it comes to this stuff, there agents who are lawyers are not. Find a patent/trademark attorney get a estimate offer to cut them in if they can win. If you incorporated the business like a llc you might have a fighting chance, since thats a legally recognized name. Your domain registration might work, but this how a lawyer makes money, they know the little ins and outs like us that know the ins and outs of internet marketing. Don't give up, but be smart.