MEtaLpREs

I'm sure the info is on this forum, but I've been searching and can't find the answer. Obviously the DD1 should be used to get the max HU output, but should it also be used to set the gain on the DSP, or leave the DSP at 0db and just set the Amp gains? Would there be any benefit to boosting the gain on the DSP to just short of distortion? Using an Audiocontrol DM-608 dsp.