Thank you Michal, that's exactly the one!!

That sure sounds like Vocal Sampling, from Cuba, singing "Un Son Pa' Cantor" from Cambio de Tiempo on the Universal Classics label.

I was watching the music block the other night and saw an all male group doing an a cappella style samba. They were in a restaurant or bar, and all of the patrons were clapping along. I tried to write down the artist or song title, but ran out of time. I would really like to know who that was, because it was spectacular.