Looking for an accessible audio batch converter

Hi,
I have a large number of WAV files that I want to convert to MP3. I've tried using the batch converter in Amadeus Pro, but it keeps crashing, before conversion even begins. Therefore, i'm looking for accessible alternatives that work with VoiceOver.
My requirements for a converter are that it can save files in a folder that is not the same as the folder where the input files are located. I also want a converter that can convert files in subfolders and save the output files in the same folder structure, like I can with Amadeus Pro. I have over 200000 files, so adding each file or folder manually or saving the output files in one big folder would not be very practical.
Any suggestions will be much appreciated.