At $2995 your Lumin D2 is almost as expensive as the 8805. It would be a shame to re-digitize the Lumin's analog output in the 8805.
Your best approach might be to connect the Lumin to the FL & FR inputs of the 7.1 input section. These inputs are not digitized so that your analog will not be tampered with. If the post (
https://forums.audioholics.com/forums/threads/pure-direct-vs-stereo.84899/page-4#post-959688) that digicidal linked to above is indeed correct, you can also have a 2.1 subwoofer output created by the 8805's discreet analog crossover circuit that (hopefully) will not molest your original stereo signal.
Best of both worlds if it all works. The only way to know for sure is to set it up and listen.