This game was mostly composed by ACE, the same group that composed the music for Xenoblade.

Emil Chronicle Online Original Soundtrack
AVCD-17943 | Emil Chronicle Online Original Soundtrack - VGMdb (http://vgmdb.net/album/5557)
EDIT: I found this OST in FLAC! Emil Chronicle Online Original Soundtrack - oOo VnSharing oOo (http://vnsharing.net/forum/showthread.php?t=153256)

Emil Chronicle Online Original Soundtrack Vol.2 ~Door of Neogenesis~
AVCD-23308~9 | Emil Chronicle Online Original Soundtrack Vol.2 ~Door of... - VGMdb (http://vgmdb.net/album/5558)

Emil Chronicle Online 6th Anniversary Soundtrack
LACA-9231~4 | Emil Chronicle Online 6th Anniversary Soundtrack - VGMdb (http://vgmdb.net/album/30020)

The first two OSTs contain some tracks not found in the anniversary OST.

These would definitely be nice to have.

BUMP!
would also like the 4th anniversary memorial complete OST

bump.

Late bump.

I found both the first and second soundtracks floating online. Haven't had luck with the 4th Anniversary CD since the one link to a chinese hosting site won't let you download without VIP account. Someone will probably have to buy the CD and rip it.
Oh, and just a note: OP's FLAC link is dead.

Emil Chronicle Online Original Soundtrack (320kbps | MP3 ) - 4shared (http://www.4shared.com/file/KN1g4Hvy/RdeathEmil_Chronicle_Online_Or.html) + Mediafire (http://www.mediafire.com/?pldu27fantn7hba) (Password protected)
Emil Chronicle Online Original Soundtrack Vol.2 ~Door of Neogenesis~ (128kbps | MP3) - Mediafire (http://www.mediafire.com/?axwkjjziefb853s) (Password protected)
Type in "eco" when the password prompt comes up.

Now, if only I can play the game... it's giving me black screens past character creation. Hah.