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Key: The Metal Idol BGM Data Disc II for Third Program
This specific Key soundtrack is solely the BGM from episode 14 (which is 90 minutes in length). The music to this episode is really eerie, and the soundtrack as a whole isn't too enjoyable. Because the producers decided to separate the soundtracks into "BGM" and "Vocal" tracks, you are left with a pretty bland CD overall. However, if you've seen the anime in its entirety, episode 14 does lack some action because half of it is just telling bits of story that you never learn from episodes 1-13.
There is one specific track, however, that shines like no other. This is probably the best song I've ever heard from Terashima (and I've heard a lot of his work with Falcom, just to clarify that). Track 13, "Passenger," is the credits music to episode 14, and it rocks. It is just a neat track through and through. Then, the last track is just a bunch of Japanese talking, so it's like best-to-worst in one track for an American :)
This neat little soundtrack can be purchased at Anime Nation for only $25!