Pentatonix

Pentatonix is an a capella group made of five members, and they've basically gone from music TV show winners to Grammy winning world touring billboard topping musical success. They cover popular music and also produce original music, and it's all a capella (well, mostly because sometimes the one guy plays his cello or they invite other artists like violinist Lindsey Stirling to collaborate in their beautiful music-making). So anyways, like I was saying, they make bumping amazing songs just using their voices. They sound like a complete band or something, but it really is just their voices harmonizing together and making very solid and well-put together sounding music. There are definitely about to be some YouTube links below.