iva d310 volume problem

I have the Alpine IVA-D310 dvd player head unit hooked up to two PDX amps (4.100 and 1.600). I've noticed this for a while but it never bothered me until I got a new intake and my car became quite a bit louder; the DVD player plays movies at a significantly lower volume than all other media. I can play CDs in there and it plays at the same volume as through my iPod, so I figure maybe the DVDs are not recorded as loud as the music perhaps? Anyways, when I play music in my car I usually have it set to 15-20 on the volume, but when I play DVDs in the car I have to turn it to the max (35) to barely hear it and that's with the MediaXpander stuff turned on (which makes it louder, but makes music sound worse). I don't really want to turn up my amp gains because (I believe) it's properly set up right now, so does anyone know any other solutions to this?

Go to page 22 of your owners manual and see "switching audio tracks".There is no such thing as free installation!

Sorry about taking so long to reply, I hadn't watched a movie in a while to test this out. Switching the audio track on the dvd just changes the stuff that's been recorded on the DVD (same as going to the setup menu and selecting DTS/5.1/commentary). My problem is that no matter what's been recorded on the DVD, it will be much quieter than any other media I can play and I was wondering if anyone knows why this is.