One thing I find very interesting, someone mentioned before (I couldn't find that post, that was from not that long ago) that since the ES9017S is an 8 channel chip, so 2XES9017S can only do 16 channels, not counting Z2,3 and Net. That means there is 1 channel short for models such as the X6800H that has 17 discrete channels not including z2,3 and net.
In previous D+M models, they use the 3XPCM5100 for Z2,3 and Net, that is a fact as there are service manuals anyone can see. The X6800H and C30 supposedly (based on seemingly reliable sources so far) has 2X ES9017S and an unknow number or PCM5102A, so it is possible that they use the PCM5102A for the 4 subouts, or the PCM5102A are still used for Z2,3 and Net and the missing subout channel will then have to share the same DAC channel of another subout, example, sub1,2, each has its own but sub3,4 share the share. When I email Denon on this, the rep's response was vague, but seem to indicate since there is only 1 LFE channel, while each subout can have its own adjustments, it does not mean every subout must have its own dac channel. I find this interesting, but I guess there is no chance of getting the truth unless D+M eventually make their service manuals available, or someone do a teardown, plus some in depth technical review/analysis.