Hi JIT,
Some questions for you:
1.
When you convert to .AMV, what settings are you using?
2.
Also, what convert tool version are you using? 3.68 or 3.57?
3.
Can you check with the instructions here:
http://www.mympxplayer.com/viewtopic.php?t=32 and see if you have the same settings? Let me whether that has sound or not after the conversion using those steps.
4.
What O/S are you using?