A Truly Evolved Format mp3PRO is an evolution of MP3, developed by the original geniuses behind the world's most popular audio file format. mp3PRO starts with MP3 and builds on top of it, instead of completely replacing it.
		Audion is now the first and only Macintosh program to support mp3PRO!

Put Simply: Better Quality with Smaller Files! It's true! When encoding a 64 kbps, MP3 starts to truly break down - sure, the files are small, but quality suffers as hi-hats go missing and bass vanishes without a trace. But mp3PRO -- that's another story. Using "Spectral Band Replication" (SBR), 64k mp3PRO files contain the original (limited) MP3 audio data as well as higher frequency SBR data. The result? All frequencies covered, but no additional size! In other words, a 636k mp3PRO file sounds as good as a 1.2M MP3 file!

Backwards Compatible, But... What happens when a person listens to an mp3PRO file on a player that doesn't support mp3PRO? Simple! They just don't hear the 'PRO' part -- the file sounds like a standard quality 64k file. But you know what? There's no easy way to tell if a file is mp3PRO or not by simply 'looking' at it. By using another player, you could be listening to an mp3PRO file and not even know it -- it just wouldn't sound as good! So, by being an Audion user, you're guaranteed all your .mp3 files will play to their full potential!