Не знаю коллеги, почему у вас Винамп 24 бита не играет..
На всякий случай, а в Винампе создана ассоциация с wav-файлами?
А рекомендации по установке MAD выполнили?
Configuration
=============
  1. Start Winamp.
  2. Configure the `plug-in` from Winamp's Preferences panel under the
     `Plug-ins`/Input section. Choose the highest output resolution supported
     by your sound card (usually 8 or 16 bits, but possibly 24 or 32 for
     `high-end` cards.)
  3. Disable the Nullsoft MPEG audio decoder `plug-in` by deleting the file
     association extension list (version 2.7), unchecking the "Use for MP1,
     MP2, and MP3 files" option (version 2.666), or unchecking the "Layer
     III", "Layer II", and "Layer I" options (version 2.33 or 2.34) in its
     configuration.
     Alternatively, you could move the file in_mp3.dll out of your Winamp
     Plugins directory (usually C

rogram FilesWinampPlugins) and restart
     Winamp.