You may want to try internet Audio MIx. you can get it at
www.acoustica.com. It will not only allow you to convert to wave but will allow you to allign your original wave file with the karaoke one. I use the original artist to set the lyrics so I don't mess up. (Works as long as the the karaoke file is the same as the original artist). I have been able to switch the wave files before clicking the create CDG file button. Note: the majority of Mp3 files will not allow for clean removal of vocals. if you want to use an mp3 file as your background music you need to consider picking up a karaoke mate from Rdio Shack as it is the only device I have found that works well with mp3s converted to waves.