Look slick, are you a product of the public education system here? 0900 on Sunday morning is too frigging early to crank the music for everyone to hear!!!
Yes, im a local, and as such i can inform you that loud music on a sunday morning is not nearly as uncommon as you think it it. On sundays many people do home chores, clean up the place, etc. and for that they often put on some loud music or the radio. Or maybe they are preparing a meal for the family, which may start early, and for that they to put on some music too.
I wasn't telling you to enjoy it, but if its not a regular thing, my advice is just bare with it, unless you want to receive critics from your neighbors whenever you do something annoying. If this becomes a regular thing, then yes, you should do something. Talk to your neighbor or the building management.
In the last apartment i lived, we had an unspoken agreement. Sometimes one of my neighbors had a gathering with friends or a full on party in the middle of a week day, and sure it was annoying, i had to wake up early. But i never complained as i held gatherings and parties too, and my neighbors never complained either.