Hi. Those thing don't really need to be conficured, they should work out of the Box. Did you try to play mp3 from different sources? Was some of those mp3s working before on that player. Also make sure you have a well charged battery. The player also support .wma audio files, does the problem still happen with those? Is it doing it with a different set of headphone?
Believe me, the FM function have nothing to do with it. An underwater effect usually come from a lack of bandwith in the numerical stream, meaning a low bitrate. That can be cause with a software decoding problem, an electrical porblem in the amplification stage just before the output or by a connection to the headphone jack that is not complete but very close to be so it act like a capacitor and filter some harmonics out. If you can test it with a wma audio file it would help to reduce the possibility of problem. Here is a link for a wma audio file to test:
It is the last one in the download option. Let me know how this one play.
The bitstream of the file and how the decoder interpret it is two different thing. Please report me how the wma file i linked is doing.
ho, and another thing, what is the quality of a radio reception on it?
That is with the sample file i linked also? What about the sound of the radio stations?