Help me integrate my volume knob with my MR816.

I’d like to integrate my volume knob with my MR816. It’s working great now, but I’m currently going out of my volume knob to my powered speakers, thus sing the DtoA of the volume knob (Tascam D-SM 7.1) and I’d rather use the DtoA of the MR816 as it sounds much better. So how would I route the following:

MR816: Out Adat to
Volume Knob: In Adam

Volume Knob: Out Adat
MR816: In Adat

MR816: OUT ???

How would I route something going to the MR816’s adat ins to the analog outs?