Sony CD Players can only play Atrac files, if you create the CD with SonicStage (or with other software, like Sony CD Simple Burner), because it has a specific file stucture. But there are some more restriction. An Atrac CD can only contain Atrac3 @ 132, 105, 66 and Atrac3+ @ 256, 64 and 48. But if you already have your music in MP3, there is no need to convert them to Atrac, especially not to higher bit rates (you won't get higher sound quality anyway), because all CD players capable of playing atrac is also capable of playing MP3 (at any bitrate, even VBR). In my opinion, the only case if converting can worth it is if you want to store a lot of tracks on a single disk, when you should use Atrac3+@64kbps.