Want tons of tunes ? Go here....
http://ubrsdlc.realsimulation.com/
Go to the Silent Hunter III Files area of the forum.
In the Silent Hunter III forum there is a thread called SHIII Gramaphone
They are in zip files and if you download them all like I have, you will have a metric TON of period music and or German radio propaganda to enhance your experience.
This is absolutely safe. All you have to do is unzip or unrar each file into your Silent Hunter III/data/sound/Gramaphone folder.
If you have a song you want to drop in there, you can just toss the MP3 right in.. but the game prefers the OGG format for music. Sometimes MP3's get a little "skippy" for some reason according to some people although I have several MP3's in there and have yet to hear any problem with them.
I put about 300 tunes in there because If I heard the song that goes "All over the place !" one more time, I was going to go crackerdog. This severely cuts down the number of times I hear it.