Yes this is the tricky part, by-laws are great an all but having them enforced and acted on is another story.
Toronto changed this by-law for noise, and actually I think made it worse. You use to only be able to play music until 11 pm at night. Now you can play music 24 hours a day, but at certain levels. It's dumb. I think this neighbour knows this as well, because the music is loud but not that loud. It's not only the loudness, but basically it's perfectly clear, I have no recourse to distance myself from the music because where our 2 properties connect our houses are on opposite sides so this shared space is where my backyard and theirs meets. Anyhow I've tried the bylaw approach, because this same neighbour also has a loud AC unit. I've had a bylaw officer out several times to investigate it, and well it's just below the threshold of the limit, so nothing can be done. But the laws don't go far enough. Because it's not just the sound that is the issue, it's badly installed, meaning when it's running it's causing this humming sound because either it wobbles, or and because it's sitting on the ground, causing this low fequency hum, and again the by law doesn't account for this because they don't monitor this range. Even my own AC unit next to my house is quieter then theirs.
The only long term plan is like
@jc100 said is to keep filing complaints and keep a record of it and eventually maybe this will help.