The xx wouldnt seem like a band whose sound - remarkably fully formed from the start - is befitting to festivals, where loudness usually carries the day. They sing quiet, patient songs - with Romy trading lines with bassist Oliver Sim - about teenage melodrama and lust.They would seem perfect for a Twilight movie soundtrack. Since releasing their self-titled debut last summer, though, they have found notable placement on Greys Anatomy and in a prominent AT&T commercial for the Winter Olympic games.Croft and Sim, who grew up in London, began playing together when they were 15 or 16 Then fans of the Killers, Queens of the Stone Age and Death From Above 1979, their first instinct was to play loud, distortion-heavy rock It was only when Crofts amp blew out and she got a new one that she tried flicking on the reverb setting.