(To clarify, because I like the group so much, it's mis-identified as Masters of Harmony, an easy mistake. Masters of Harmony is one of the long-time perennial winners of the international competition -- and with another group, Vocal Majority, the two had won the top prize 15 times in 24 years. But then in 2004, the Ambassadors of Harmony finally beat them both and made it into the winner's circle. And five years later in 2009 they came back with an amazing rendition of "76 Trombones.)
I recognized them immediately from their director, Dr. James Henry, who stands out in the cover-graphic on the video (looking a bit like the actor Richard Kind), but also the video itself when it runs identifies them as the Ambassadors of Harmony. However, I sometimes have to double-check which is Ambassadors and which is Masters. By the way, though this fellow, Dr. Henry, has been the leader on all the group's videos I've seen, this more-recent one brings a joint-leader who shares the direction, which surprised me.
What I most-like about the Ambassadors of Harmony is not only how rich their singing and arrangements, but also because they have a great sense of showmanship, and put on far-more intricate performances than most. (You can see that in the "Top of the World" video Mark posted.)
Much as I like so many of their performances, it's that winning-"76 Trombones" number that always leaps out in my mind. I posted it a long while back, March, 2013 -- in fact, the third month in after I started this site -- but a whole lot of new folks have joined here since, and since it deserves an encore, here it is again.
It's enjoyable from the first, but stick with it since that's when they start throwing in the twists and turns that gets the audience roaring in appreciation.