So, my darling sister was kind enough to DVR the Sing-Off for me so that when I watched Mads before Christmas, I could watch it. And, one of the groups that I really, really liked (and they were cute, to boot) was this group called Beelzebubs, from Tufts University.
Naturally, I just looked them up on YouTube (because that's what you do when you miss something on TV or want to revisit it) and they're an a cappella group, so there's no background music that's not coming from their mouths and their microphones. There's nothing that's not coming from them.
They opened with Magical Mystery Tour by the Beatles. And then they did one of my favorites - Come Sail Away by Styx. I have found them on YouTube and are sharing them with you.
Magical Mystery Tour
Come Sail Away
I own absolutely nothing. I'm just passing on the good word.