Do you not have to convert the music to Sony's format using their software? I had one of the early Sony mp3 walkman models (the circular "network walkman" I guess it was called)... you couldn't actually transfer mp3s to it, you had to use their software to transcode it (probably decreasing quality). It was still awesome, though!
Nice, yeah mine was a very early one, maybe ~2003-ish. You can see the manual here[0] where they describe "Transferring audio files from the
computer to your Network Walkman" on page 12. It's not said explicitly in the manual but the device wouldn't actually play mp3s, only ATRAC format which the SoundStage software would convert to automatically when you transfer the music to the device. Maybe user backlash resulted in them directly supporting mp3s in later models, as I know I was super ticked about it and didn't buy another Sony music player (eventually bought a 30gb iPod with Video).
