Please don't make "bump / anyone?" posts....
My guess would be that the General MIDI implementation on the Treo and on the Mac use significantly different instruments and/or there is no instrument identified for the tone in the file, and so it's being played on instruments with very different dynamic ranges on the two.
If you really want it, you might try opening it in some other software besides Quicktime, and when you find something that works, just convert it into a digital audio file (MP3, AIFF, etc). Or even try another computer, e.g. Windows, and see if you get it to play as you like, and then convert it to an audio file.