Transcoding in general is not a good idea. However, I have found that mp3s that have a good enough initial bitrate, such as 192 or higher, that the results when transcoded to atrac are in general very listenable. There will always be some loss of sound quality when doing this. You just have to decide what is good enough for you. Anyway my NW-S706F sound reproduction is so good that most stuff sounds good anyway. Even the 64kb stuff has surprised me. If I can I use the original CD to make all my atrac files, this assures the highest sound quality.