Since long I was used to connect the near field speakers (Geithain RL906D) to the UFX+ as the D/A conversion was already very nice and an improvement compared to the UFX. The ADI-2 Pro (connected via ADAT2 to the UFX+) I used only for phones (Audeze LCD-3).

Up to now this was a very nice setup and I controlled everything via the ARC USB. Today I experimented a little bit and changed my setup "radically" to connect also the near field speakers to the ADI-2 Pro

This resulted into a wonderful enhancement of sound, including the nice feature of dynamic loudness control.

Many thanks Matthias & RME team for the very good and wisely chosen additions and enhancements to the ADI-2 Pro by firmware upgrade. Really works like a charm

The remap key functionality is "just right", its good that you changed the behaviour to use the remapped function by default and the original key function by pressing the key a little bit longer, this feels comfortably when operating the device.

Now I am using the ADI-2 Pro
- to switch between Phones 3/4 and Line Out 1/2
- to entirely mute everything if required (also can do this still on ARC USB) and
- to turn dynamic loudness control on/off for Line Out 1/2 (speakers)

1st I thought there is much more work involved in terms of routing changes, but actually I got it working within fewer than an hour including to cross-checking the handbook.

Here the few configuraton steps on the ADI-2 pro to achieve this setup, the most important in Bold, the rest is customization:

Options -> Device Mode:
Basic Mode: AD/DA
Phones <==> Line 3/4

Options -> Hardware/Diagnosis:
Remap Keys: ON
VOL Key: Default
I/O Key: Toggle Ph/Line
EQ Key: Loudness 1/2
SETUP K.: Mute all

I/O -> Main Output 1/2 -> Settings:
AD/DA Source: Auto
Auto Ref Level: ON

I/O -> Main Output 1/2 -> Loudness:
Bass/Treble Gain: +7 dB (default)
Low Vol Ref: -45.0 dB

I/O -> Phones Out 3/4 -> Settings:
Source: Auto
Auto Ref Level: ON

I/O -> Phones Out 3/4 -> Loudness:
Bass/Treble Gain: +7 dB (default)
Low Vol Ref: -50.0 dB

The VOL key I left intentially free of re-mapping as I am used to quickly browse through the "Volume/Balance"
and "Dual Volume" displays.