I have had this problem occasionally with individual sound files. Some of the volume problem may be fixed by adjusting the volume of the podcast itself (or just the individual files). In Itunes, right click on whatever you want to change (individual file or whole DIS Unplugged podcast if this is a chronic issue for you) and under "Get Info" there is a "volume adjustment" bar which will change the volume at baseline. More of a work-around, maybe, but if you get in there and find the volume is already adjusted DOWN, there's the problem. Hard to believe it's an encoding problem if it only affects some...