OK here is the thing, it doesn't work like that. The MP3 PLayer is going to try to communicate with the device on the other end of the wire in WINDOWS speak! The android doesn't really understand that protocol, windows speak. There is nothing there to translate the two for each other. Does the MP3 player have bluetooth? Can you pair the table to the device using bluetooth? Bluetooth would be a protocol (transport) they both could use!
If you can pair them, then the tablet should see the MP3 player as a DRIVE. Place your music from the tablet onto THE DRIVE!
Now, understand, the music can't be in both places at the same time, you are probably only allowed ONE license.
Let us know! Have FUN!