There is really no separate control for the DVD Sound Level at least no hardware potentiometer that adjusts it, it is all in the software. I have not seen any controls for it in the software of the NAV either... DVDs are ALWAYS lower in volume then CDs just so you know, its the nature of the beast since they are 5.1 encoded. I am pretty sure that we will have to live with it... since all signals are processed in the multi-function unit then sent to the AMP then to speakers so increasing signal levels from the unit will change ALL signals, as far as increasing signal levels from the DVD, well that is a different matter, I would not touch those since these are pre-amp level signals and you can overload the circuit then again... the only way to do this would be to measure the actual levels coming in from CD changer vs. DVD player I can post the REPAIR MANUAL DIAGRAMS if you wish to measure the voltage yourself, SHOULD be the same..