You can connect the loudspeakers to the UFX that you have and take out the ADI-2.
If it is redundant for you, no one can tell.
With a new UFX lll you have the newest interface and no need to connect further units.
The analog outputs of the interfaces are all very good. (for me)

Anybody willing to comment on the conversion ADI-2 FS vs RME UFX III?  Is one better than the other or are they on par with each other? 

Thanks

FWIW, I was using an ADI-2 Pro fs with a ff800. When I got the UFX3, I hooked it up the same way (adi for monitors) then switched to the UFX and was very pleasantly surprised. Sounded really good to me, and I took the ADI out of the chain.

I didn't do a bunch of a/b testing, but I could tell immediately it was more than fine. One thing I notice with that stuff is after using it for a while, or playing through it, I either still like it after a while or something is bothering me. That's sort of my super unscientific test, but it holds some truth to me from past experiments.

You could test yourself if you get one and know for sure, and then sell the ADI if you really wanted to find out how it works for you. If you sell the ADI first, you might always be second guessing yourself. Just a thought.

EDIT: rephrased, some comments on FS clock, please re-read.

What do you have, an ADI-2 FS or an ADI-2 DAC FS? Could you kindly stay consistent in your product descriptions? Thanks.

Option A) if you connected an ADI-2 DAC FS as clock slave:
- D/A conversion happens in both cases (UFX, UFX III) on the ADI-2 DAC FS
- using it's internal FS clock
In this case, no difference whether you use UFX or UFX III

Option b) if you connected an ADI-2 FS as clock slave:
- D/A conversion happens in both cases (UFX, UFX III) on the ADI-2 FS
- but if I remember right clock is being used from clock master (either UFX or UFX III)

So, if I recall it right, the ADI-2 FS would use the clock from AES which is in the case of UFX III a FS clock.
Then it could be, that there is maybe a little difference in sound.
But I also remember that it has been mentioned on forum, that the introduction of FS clock alone with the ADI-2 Pro FS it delivered only better measurable but not audible better results.

The question is
- what device you have exactly and whether I remembered correctly that ADI-2 FS would use the clock from AES and
- whether you did proper blind testing to avoid any bias ..

I think there is a good chance that the difference is based on expectation / psychoacoustic effects, if tests have not been performed as blind tests with quick A/B tests possible.