Hi Larry,

Transition is straightforward if you know what to do.

Below you find a guideline, as I have done similar things a couple of times already. I hope I didn't forget anything. :-)

Make a note about your 12Mic port settings, whether you use 48V, Inst and the Gain settings.
You will need it later to set the proper Gain settings in TotalMix when configuring Auxdevice (remote control via TM FX).
Auxdevice is luckily available now for the 12Mic and works fantastic.
By Auxdevice you can save and recall the Mic settings for the 12Mic in TM FX in TM FX snapshots and workspaces.

Backup your system before making changes

Before modifying the system, it is advised to make a Backup. Under Windows, I strongly recommend making a disk image using Macrium Reflect Home. This is the only product which works really reliably and fast. They also have mechanism to reduce the restore speed by writing only blocks that need to be changed, this also reduces the wear on SSDs.
A restore of a filled 1 TB SSD doesn't take longer than 10-15 minutes.

Install new TM FX version with Auxdevice Support

Install TM FX v1.97b1 which gives you Auxdevice support via MIDI over MADI.
https://forum.rme-audio.de/viewtopic.php?id=40049

BTW, if you prepare for that now, do not wonder that it does not work now without MADI.
The 12Mic has no MIDI port, so only MIDI over MADI is possible to use for remote control.
With ADAT it is not possible. RME uses here unused bits in the MADI protocol header to transfer MIDI information,
hence the name "MIDI over MADI".

MADI cabling / SFP

I recommend using MADI via optical multimode cable to get also galvanic isolation between the devices.
For that, you require an OM4 duplex cable with LC-SC plug.
Cable like this one
https://www.kabelscheune.de/LWL-Kabel-L … 5-OM4.html
You need not more than 0.5 - 3m if the devices are in a rack. Do not bend fiber cables too much.
If the devices are one over the other with a little space for air flow then 0.5m are sufficient.
Get a second 1m cable as spare / alternative.

For the 12Mic you require an SFP module for multimode with 1310 nm wavelength.
Best you get the RME multimode module from RME not to pick the wrong one.
https://rme-audio.de/de_sfp-module.html
You can't use single mode SFPs, or multimode SFPs with a different wavelength or SFPs with a special firmware for vendors like Cisco, Intel, Brocade (to mention a few).

MADI settings on UFX III and 12Mic

Configure the MADI in the UFX III driver settings to use 96k Frame Format.
The same you select in the 12Mic using the front menu (not possible through Web GUI if I remember right).

Configure MADI routing on 12Mic via Web Interface

Access the 12Mic via Web Browser to setup the MADI routing.
- From Mic inputs 1-12 to MADI (assumed optical here as it delivers you also galvanic isolation, which is an advantage)
- Passthrough of MADI ports 13-64
- From MADI channel 1-2 to Heaphone output, then you can use HW Output MA1-2 to play on 12Mic phones output

Auxdevice Support (remote control of 12Mic via TM FX)

Setup Auxdevice Support as highlighted in the forum article.
Select MADI Port 1-8.
Configure Upper Half for 12Mic Port 1-4
Configure Lower Half for 12Mic Port 5-8
Configure MIDI IN and OUT to be UFX III MIDI port 3 (if optical, 4 if MADI via BNC) for Upper and Lower Ports.
MADI ID is not so important in this case, but you can give the device the MADI ID 1.

Then select MADI Port 9-16 and configure only the Upper Half for 12Mic Port 9-12, the lower part stays empty.

Mic Ports / Routing

When switching to MADI your Mic inputs will change from ADAT1-12 to MADI 1-12.
As you might know HW inputs are per default directly passed through.
So if you use recording templates in your DAW you need to change them to use MADI1-12 instead of ADAT1-12.

Regarding TotalMix FX routing its also easy and straightforward

Backup of old settings

1st make a backup of your current settings
- Save Workspace as ....
- Save Workspace also to Workspace Quick Select Slots
   - Slot #2 the current settings
   - Slot #1, later when the transition to MADI has been finished

In every TM FX snapshot (1-8) check every HW Output / Submix

Ensure you are in submix mode (upper right corner, blue field).
Go through all of your used snapshots (1-8) in TotalMix FX.
Click to every output/submix and check if any of HW Input fader ADAT1-12 are raised.
If yes: raise the fader to the same value of the corresponding HW Input fader of MADI 1-12.

As Auxdevice support (remote control of the 12Mic via TM FX is possible) you can also set the proper Gain Settings.
I told you to make some notes about the Mic Port settings, now you can enter the proper Gain as well for the inputs.

Once you checked all submixes of a Snapshot, you can store the changes to this snapshot and proceed with the next.

Save the new settings

Finally, save your modified setup to a Workspace (with another filename not to overwrite your backup).
And also save it to a Workspace Quick Select Slot, I propose to use Slot 1 (of 30).
Then you can at any time switch between Workspaces using ALT-1 and ALT-2 should there be demand to check something.

This seems to be a problem of your DAW, in Cubase it tells you the channel names.

I am not sure why you need to look into the TM FX matrix.
You see the order of channels also in the mixer view, scroll from left to right and observe the names / order of names.
Then take a piece of paper or use Excel and write the numbers down.

The RME channel numbers / assignments follow an easy logic.

First analog (Line Level Inputs, Mic Inputs) followed by digital channels (AES, ADAT, MADI).

See here an example of Cubase: