Inspiration for soundtrack

The music that I wish to create for my media product will be dark, ambient and will be noticeable enough to unnerve the audience, but subtle enough so that it does not detract from my film. On Youtube I have found some examples of the general feel of what my soundtrack will be trying to emulate.

http://www.youtube.com/watch?v=n1vjTJTRn48

^ The above sountrack is entitled 'Haunted Sky' by Robert Christopher, and it is a good example of the kind of non-diegetic sound I wish to use within my film. It does not utilise any obvious instruments that can be picked out (such as guitar and piano, etc) so it has an eerie, almost natural feel to it, which is good as I do not want the audience to be overly aware of the soundtrack, but rather be immersed in the entire package. The music itself is also not very overpowering in that it will not avert attention from anything happening in a scene if used as a soundtrack.

http://www.youtube.com/watch?v=kxuvy-_F8iw

^ The above soundtrack is entitled 'Atrium Carceri', and is different to 'Haunted Sky' in that it utilises more recognisable instruments (such as chimes throughout and vocals part-way in) instead of just being an ambient soundtrack.  It would be an effective soundtrack to base my own soundtrack off since you can feel the tension building while you listen to it, which could be used to my advantage in my media product, as it reflects the horror/thriller genre. However, this soundtrack appears to be more technically complicated, both to create and listen to, and I think that this may detract from the overall experience of the media film I wish to create as the audience may be more focused on the music than what is happening aesthetically.

From these sountracks I have gathered that, in order to create a soundtrack that will be unnerving, engaging, but subtle enough so that it is not obvious that the audience is hearing a soundtrack, as this will make my media product even more unsettling. To create this I will use minimal instruments and instead utilise more ambient sounds to create a soundtrack that will enhance the aesthetics of my film rather than distract from it.