miggs,
I'll stumble all over this, but I wanted to put something down because I see no one has responded just yet. Take the following with a grain of salt, but hopefully it will help you in your web (or forum) search for this. I remember a good explanation being posted here last year sometime.
I believe that DD tracks pass a parameter that allows a decoder to set the baseline volume to some standard. To meet that standard, some with be reduced in volume (-dB), while others will be increased in volume (+dB). I noticed this when I got a new receiver about three years ago. I think that my older receiver did it, but it didn't show it on the display like my new one.
I don't know if it can be disabled. I'd look through your owners manual, but I have some yard work to do - so I'll just point you to that. Check out the manual for the Yammy and the DTV receiver and see if there are any options.
Hopefully someone more knowledgeable will chip in here. Good luck!
Adam