Ok, so you have a housewarming coming up. I would quietly talk to a few neighbours, under the excuse of inviting them. Sayyou are a bit worried by the music, ask them to say honestly how they feel. If they do say there is an issue, then you have two options.
YOu can tell DH that people have said this.
Or, if you have no credibility with him, ask the neighbours to mention it at the housewarming, to him direct. Explain that he thinks you are exaggerating and it would have more credibility coming from the neighbours. Stress how much he wants to be welcoming and friendly but you think he has got the wrong idea of how to go about it.
Villages are not necessarily quiet all the time, especially if farming goes on. There may well be live music nights in the pub or a gang of locals who meet up to play, which would suit your DH as he is a musician, u say. So hopefully the locals will seize the chance to divert him onto site hitting more constructive.
It won't happen spontaneously, though, you need to make people feel that they can say something.
FFs do not go with the anonymous note idea, I hope that was just a joke. He will tank his neighbours are cowardly, underhand and snobbish and he will not give a monkeys what they think from then on.