Download and install the MediaCoder Audio Edition application (see link in Resources). Run the program.
Click the "Add" button, located in the left corner of the top navigation buttons.
Select "Add Folder" from the context menu.
Navigate to the folder containing the WMA files to be converted. Double-click on the folder to add it to the application interface.
Specify the desired output folder under the "Generic" tab.
Click the "Audio" tab to set the audio-specific properties.
Select "MP3" as the output file type in the Audio section.
Make sure that the "Preserve Original Folder Structure" checkbox is checked. This will ensure that your MP3s will be arranged the same way as the original WMAs.
Adjust any additional audio settings specific to the batch job.
Click the "Start" button at the far right of the top navigation buttons to begin the conversion. MediaCoder uses the term "transcode" for the conversion process. Once the batch conversion is complete, the entire directory of WMAs will have been converted to MP3 files.
Test the new MP3 files in an audio player to ensure that they converted with no errors.