Being quite deaf, I like the audio quality of my 505. I can't hear highs or lows without large and powerful hearing aids, so the 505 is the perfect mp3 player for me.
Perfect except for the inability to cycle songs, make play lists, automatically repeat songs, turn off the music without turning off the entire device, leaving the music playing a draining the battery overnight instead of every two weeks with just books.
Come to think of it, maybe the 505 isn't the very best MP3 player....
Stitchawl