Well, I'm kinda surprised but I found a better way to do all this and achieve bass management without having to go through the DAC in the my Marantz 8802A. This allows me to use the subwoofers with my LS50 Metas and my outboard DAC without double-bass issues. Long story short, on Denon and Marantz preamps you can turn on the normally shunned setting LFE+Main and it will send an equal signal to the mains and subs at all time, even in Pure Direct Mode. To do this correctly you could use whatever bass optimization you choose but the outboard DAC is treated as analog passthrough with no filtering.
This was most important to me in regards to multi-channel SACD that really wants full range in all speakers, especially for high dynamic range stuff like 1812.
Here's what gave the insight: