After the a cappella group's whirlwind year, we honor the top 10 best Pentatonix songs to date as 2016 nears its end.

PHOTOS: Biggest tech flops of 2013 – so far Pentatonix’s second album, “PTX V2,” debuted this week at No. 10 on Billboard’s Top 200 album chart. Three of the group’s members, Scott ...