I use the Fraunhofer Codec or an encoder DLL to compress to MP3, but the resulting File has the file extension “.wav”. What is wrong?

EAC will write WAVs when using codecs (EAC emulates a codec for the MP3 DLLs). This has the advantage that it will play with any media player, when any version of the Fraunhofer codec is installed (even the free one, called “advanced”). If you want “pure” MP3 files (without the WAV header in front of it), just select the option “Do not write WAV header” and specify the appropriate file extension below (“.mp3”).