Conversion of mp3 files to oma file format

It looks like that conversion of MP3 audio to OMA format (used in certain Sony portable media players) is possible, however you would have to find a copy of the discontinued Sony SonicStage software. Once you have the program installed, you can simply add your .mp3 to the library and convert it to OMA format from there.  This is likely the only way how to achieve this conversion, especially because .oma files are not well-supported.

Open MP3 file    Open OMA file