PTXO

SPREAD VIRALLY BY MOUTH: Madison Gate's Pentatonix is a young a cappella quintet specializing in covers, mash-ups and medleys of Pop hits, and they've been quietly building a massive viral audience for a while now. Well, the quiet part is over, as the band's new album, PTX, Vol. 2, sits at #2 on the iTunes album chart (behind Eminem) and #1 on the iTunes Pop chart. They got a mainstream boost this week thanks to an Ellen appearance (during which they broke out their "Evolution of Beyonce" medley) and the YouTube Music Award they won with violinist Lindsey Stirling for Best Response Video (for their rendition of Imagine Dragons' "Radioactive"). Today, Mashable showcased their Daft Punk medley. But before all that happened, Pentatonix built their online audience; they've since cultivated nearly 2 million channel subscribers and crazy view counts on individual clips. "Radioactive" has earned 44 million views; their centuries-spanning "Evolution of Music" (which begins with an 11th Century Gregorian chant and finishes, four minutes later, with "Call Me Maybe") picked up 22m; and their take on Lorde's "Royals" has drawn 11m. The Daft Punk clip garnered 3.2m overnight. The fivesome's domestic tour itinerary includes stops at theaters like the Beacon, Fox and Orpheum; the European trek, which kicks off next week, is sold out. (11/6p)