Yes, but believe me, you really
don't want to use your 505 as an MP3 player

. Even the cheapest "real" MP3 players wipes the floor with it. The MP3 player on the 505 is one of those things that the marketing people probably said they "had to have". It is primitive in the extreme, and "dangerous" too. It doesn't have a "stop" button, only a "pause", and it's all too easy to leave it playing accidentally and drain the battery flat.
Much safer not to have any MP3 files on the device. Use the Reader to read, and a real MP3 player for music.