I am having trouble outputting a stereo mix, the left channel is always 6db
lower in output. I have assigned the output to four separate pairs of outputs
with the same problem. The meters in both DP5 and the RME mixer show
everything to be fine,yet the level coming out is 6db low on the left channel.
I ran a test tone out of DP on stereo outputs as well as each output set to mono and the corresponding output was always low.Could this be a driver
problem or am I just forgetting something? I am thinking its unlikely I lost
the even numbered outs,especially since everything sounds fine,just quieter.
Most likely I am just retarded,but I have checked everything I know.

Try updating the firmware. Although it dpeends on how the thing is designed, it seems less likely to be an electrical problem since you have proven each output to be good.

You could also check if the low-level output is acting one-legged (ie. either the hot or cold leg is not present/sitting at ground potential).

A silly question, but have you tried using the matrix to switch L/R to isolate a driver/firmware issue from the physical output connectors and wiring? Not sure that will make any difference, but probably worth trying. Also try swapping the output connectors to see if your wiring is just bad?

Also, have you tried contacting RME. They were super helpful when my first 800 died and just sent me a brand new one....of course it was only a month old or so...