1

Download Winamp 2.7. Winamp is a popular media player that can read many different audio file types. Winamp 2.7 has a specific plug-in that allows you to easily convert audio files into MP3. The old version of Winamp is still available on sites like OldApps (see Resources). Once it has downloaded, follow the installation screens to install Winamp 2.7 to your computer.
2

Download the SNESamp plug-in (see Resources). The SNESamp plug-in makes it possible for Winamp to read SPC files. When you click on the setup, screens will open to walk you through the plug-in's installation.
3

Open Winamp and go to "Preferences." Click on "Plugins" and click "Output." When the screen comes up, select the plug-in "Nullsoft DiskWriter."
4

Click "Configure." When the window opens, click on the "Output Directory" button. Put a check next to "Convert to Format," and click on the button with three dots next to it. Select the MP3 format and click "OK."
5

Pull the SPC files you want to convert into Winamp. You can add audio files to Winamp on the File tab. Click on "Add Media to Library." Drag-and-drop individual files or whole folders of audio from the left window into the right window to import into the Winamp playlist.
6

Play the playlist. Make sure the first SPC file in the playlist is highlighted before clicking the "Play" button. The SPC files will play in order. When the entire playlist has finished playing, the Nullsoft Diskwriter plug-in will have automatically created MP3 copies of each SPC file in the output folder that you selected.