HA Mode on UR816C

The following is described in the product page of the UR816C:

“HA mode is a special mode that allows one of a pair of UR816Cs to be used as an eight-channel mic preamp and ONE SET OF MONITORS conveniently used with both units”.

The description of HA Mode in the User Manual says:

“It can be used as an extension of monitor output.”

Does this mean that using two units would give me up to 20 analog outs (2x10) being controlled by a single monitor section (Output Level, Dim and Mute)?

One single monitor section is right, you can do that in the mixer.
But 20 Independent analog outs to my experience not.
Because monitor out is always used by Mix 1. And you have 4 mixes, so 3 left for the other analog outs. My guess would be 14 independent analog outs.
I use a UR816C with a ADA8200 and can only produce 14 independent analog outputs.
So I would never buy 2 expensive URC’s, I can’t see no benefit over 1 URC + 1 ADATunit such as the ADA8200.

The reason why I ask is because currently I use the UR816C for 5.1 surround monitoring, but I’m trying to figure out if it would be possible to use two units for Dolby Atmos, which would require 12 monitor outputs (7.1.4). Ideally I’d like to be able to control Level, Dim and Mute from a single unit. I’m not looking for independent outs (like for headphone mixes).

I agree using two URC’s would be a bit overkill, but right now the dspMixFX only allows assigning analog line outputs to be controlled by the front panel. If it would let me control the digital outs as well I could use just any other DA. Is this something that could be done in a firmware upgrade? The way the manual describes HA Mode gives me that impression, that two units would actually increase the number of outputs controlled by the front panel of one unit alone (to avoid needing an external monitor control).

I don’t know the answer to that I am afraid. But do not count on any firmware upgrade by Steinberg with your requests.
I rather would buy an Behringer dekstopmonitor controller, way easier I guess.

Off topic sorta, does MIDI work in the HA enabled device?