Path ~
Projector to DI's to
snake to board to show films with audio from soundboard
Maybe you already got your answer, but the way you're describing this is confusing enough to warrant clarifying. Normally the audio path is described from source to destination. What's your source? Is Marshall correct in that your DVD player is built in to the
projector? Where are your speakers? Are they built into the
projector or separate?
The most common way to do this would be DVD player -> DI boxes ->
mixer -> amps -> speakers. In this scenario the red and white outputs of the DVD player, using whatever cables you have available, would go to the DIs - left to one DI, right to the other. From there, the
mixer would
send the signal to your speakers.
Some projectors have audio inputs to use the speakers built in to the
projector. If this is the case and if the speakers are adequate for your needs, then you can go simply from the audio outs of the DVD player to the audio ins of the
projector. This doesn't sound like your scenario, though.
Basically you need to identify what's an "out" and what's an "in".
You mentioned that the audio was "weak". Does that mean you couldn't get enough volume, or did you mean "weak" as in "lame" - you missed the stereo
effect? It should be completely possible to get satisfactory audio on a
mono system, either using a DI box that can combine 2 inputs into 1 output (like the Whirlwind PCDI or the Radial ProAV1), or by using 2 DIs to a
mixer panned center. If you have a stereo
speaker system then you can do as you describe where you pan one
channel left and one right.