Hanging out in Parque Lleras when these beautiful bastards broke out in song. They afterwards gave me their card and I discovered they are called Grupo Son Vallenato. That bald guy is a firecracker and thrust out his hand for cash almost as soon as I stopped filming, which reminded me that, yes, this is the tourist area. I wish I had had more than 2000 COP to give them but they seemed pacified.
Here is the Facebook they had on the card, which looks like the private Facebook of the accordionist? https://www.facebook.com/sonvallenato.gonzalez