iPad 2 apple dock audio out select?

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Have been searching for a while online and on the forums and had to ask. I am running a hdmi to dvi cable into the hdmi adapter for the iPad 2 to run video through a computer monitor. I am plugging the adapter into the apple dock I just got but the line out audio no longer works, I am guessing because it wants to send the audio through the hdmi? Is there a way to decide how the audio is output from the device, I am trying to install the dock in my car but do not want to run a cable to the audio jack on the iPad itself, I would like to keep it clean and all the wires tucked away. Any help would be great.