darkbyte is right, in that mp3 uses (and any valid mp3 file must use) an MDCT - which is entirely absent from mp2. So there's no way of putting the mp2 data into an mp3 file without loss. It's a different, lossy, representation of the audio signal.Just renaming something.mp2 to something.mp3 (or something.mp2.mp3 so you know what it really is) is a handy workaround for lots of equipment - often the front end only looks for ".mp3" files and can be tricked into letting mp2 audio through by the simple renaming. Mp3 decoders are supposed to decode mp2, and many will if you can force the front end to pass them through. Doesn't always work though.I just transcode using fb2k/lame if I need mp3s. I pick a higher target quality/bitrate than normal to try to minimise transcoding artefacts. I only transcode if I have to. Where space is less important than compatibility and sound quality, I just go to FLAC. If I want to keep the recording long term, I just keep the mp2 version.Cheers,David.