What are you patching to your ADA8000?
If its an Aux send then go to the EQ section in the Aux Master and add 8 dbs gain to the output. ( Of course after all eqing is done and if there is headroom available there. One could always get some gain in the compressor stage if it is not in use...) This will match the ADA's output to your omni outs and L/R outs. It is of course to note the ADA has less headroom. It will struggle with amps that require very high dbv input levels. I have 2 and have no problems running my monitor amps or self powered boxes with the ADA.
Douglas R. Allen