With default client you mean the web page "Play Button" i guess. Did you dl the soundbank.rar
http://s000.tinyupload.com/index.php?fi ... 0232882679 , unpacked and dropped soundbank.gm in the JRE XX/lib/audio folder ?
If you don't have that JRE XX/lib/audio folder create one and drop the soundbank.gm there...now when the client starts there should be music immediatly starting on the char screen...
You might have a look at Documents and Settings/User folder - there should be a folder .haven - look at \cache\res\sfx - it should contain cached music files...
Or you look into Java Control Panel -> General Tab -> Temporary Internet files -> View -> Ressources ( it shows Java downloaded and cached files which are in Documents and Settings\User\Local Settings\Applicationdata\Sun\Java\Deployment\cache\... - i might have folder names translated wrong - i'm on a german system)
If you're using Ender client the music res files are in haven-res.jar (unpack with 7zip): res/sfx...
"Codecs" are GeneralMidi (soundbank.gm) and OggVorbis (jcraft's jorbis ) both with Java Sound API of JVM ...