You guys can also try re-encoding it to a lower MP3 rate or use AAC instead. My Pearl seems happy with the following:

AAC: 44.1KHz, 48kbit
MP3: 44.1KHz, 96kbit

I think the AAC tones sound a little better, but really they're both good. If you want a louder ringer also adjust your Gain to like -0.5 or -0.1 ; if it's like -5.0 or something, that's your problem -- encoded too softly, so to speak.