Just FYI, and nothing extremely scientific...
Well I am doing some battery tests running stereoX1 (akg460`s <1ma per), 24/48, no phantom, all lights and features on. I burned through the first dvd battery (5400mah) in @ 11 hrs. This gives me a rough calculation of @ 490ma power draw. With the dual dvd system in place I went through a 16 gb card (16hrs) with no problem, and I have inserted another 16gb card to see how long this will actually go. I am down 1 green light on the 2nd battery, and I have been running for 3 hrs thus far. These results are very encouraging, and means that festival season is covered.