The No Win Scenario

I'd like to describe a hypothetical situation and find out whether anyone can see a legal or non-legal way to deal with it. Here it is. A couple live in a condominium in a nice part of town. Note especially that this is a condominium which is owned and not an apartment which is rented. The condominiums are two stories and the couple lives on the first floor. There are about 100 condos in the complex. One day a new neighbor moves in upstairs, a 20 year old man. It soon becomes apparent that he has no job and is not a student. He has no visible means of support. By day he spends hours sitting on a chair on his balcony or else is gone for part or all of the day. Almost every day, many people, come to his apartment for a few minutes or a few hours. All of them are between about 18 and 25, The traffic is about 10 people a day, not including his parties, which I am getting to. At night, one of two things happens. About every other night he has a party. The parties have about 15 guests, and are always rowdy. The couple below hears loud footsteps often jumping or running loudly, whooping and laughing. The parties can begin as early as 7 pm (or later) and last until as late as 4 AM (or earlier). That is to say, the starting and ending times of the parties are random within those limits. On the nights when there are no parties, the man upstairs will return between 1 AM and 3 AM. Both when he has parties and when he doesn't, he goes to sleep with his music going all night long. He apparently prefers to sleep with music. Both the music he has for parties and the music he sleeps by is always just on the borderline of being within the bounds of decency. It isn't loud in the condo below, but is clearly audible - probably not to the point of illegality - but it is annoying and almost impossible to sleep through. The couple buys a white noise generator to make it easier to sleep. This helps, but not quite enough. A couple of times after the man moves in upstairs, the husband politely asks him to try to control the noise late at night. The man upstairs always says he will, but the changes are always minor and temporary. In summary, there are often noise problems during the day and almost always all night long, but the music component of the noise is always just barely withing the bounds of decency, yet is still very unpleasant. The concominium board is generally sympathetic, but toothless and ineffective. Does ths couple have any recourse legally or otherwise?