Can I convert .mp3 audio files directly to .sesx format?
Converting MP3 Audio Files directly to Adobe Audition Sessions (.mp3 to .sesx conversion) is, per se, not possible, since SESX files do not contain any audio data.
You can, however, import MP3 audio files to Adobe Audition in order to either create a new SESX session, or simply import the MP3 file to an already existing SESX session.
We are not aware of any audio editing software or (online) conversion tool capable of converting MP3 to SESX.