I want to use a self made MP3 for my answering machine (iPhone 5 with O2 provider). I tried to find a solution to upload the MP3, but it seems this option is not available for O2.
So I tried to use my speakers, but the quality I get is really bad.
This is why I am trying to attach my PC line out to my iPhone line in. This way I do not loose any quality, at least on my side.