If anyone still cares about this, you should know that a dude named Dio posted a torrent containing a Flac rip of this OST.
NyaaTorrents >> Torrent Information >> [PCXG-50181-2] ????? (Shinsekai Yori) Original Soundtrack CD1 - Pony Canyon (OST)[FLAC] | Anime, manga, and music - Just say the word (
http://www.nyaa.eu/?page=torrentinfo&tid=381167)
Alternately, you may wish to get a 320kbps MP3 rip. You can do so here:
[2012.12.07] Shinsekai Yori Bonus CD 1 - Original Soundtrack | Hikari no Akari ║ OST- Album - Singles (
http://www.hikarinoakariost.com/2012/12/20121207-shinsekai-yori-bonus-cd-1.html)