blzbub, Not much difference between 3.57 and 3.68 if you are converting at 128x96 but if you want 128x128 then you will need 3.68.
Try some of the samples in the download section and see if the volume problem exists on them as well, if so it may well be a player issue rather than a conversion issue.
http://www.mympxplayer.org/sample-videos-dc7.html