Hi,
I put some information together for you and hope it clarifies the topic for you.
For unbalanced connections, you should better not use balanced cables with TRS plugs, check your UFX II manual, ch 19.1, 20.1:
https://www.rme-audio.de/downloads/fface_ufx2_d.pdf
https://www.rme-audio.de/downloads/fface_ufx2_e.pdf
"When using unbalanced cables with TRS jacks: be sure to connect the 'ring' contact of the TRS jack to ground. Otherwise noise may occur, caused by the unconnected negative input of the balanced input."
I wouldn't experiment just because it seems to work, and you don't experience any interference. It doesn't make any sense to think that a balanced cable could contribute to better quality in any way.
If your connected device doesn't support a balanced connection, then it doesn't have the additional circuitry needed to receive and filter out the interference signal from the difference in the “wanted” audio signal. And that is the main advantage of a balanced connection and that, combined with the higher signal level, you can use longer cables in the studio and on stage without any problems.
Analog Port – unbalanced connection
An unbalanced connection is made via a cable with 2 wires: signal carrying conductor and shield. The connectors are typically TS plugs (tip, sleeve). When recording microphone signals or using long cables, unbalanced transmission is highly susceptible to external interference. Here, only lower levels are used, consumer level = -10 dBV (which is only 0,3Veff).
Analog Port – balanced connection
In the professional environment of a recording studio or on a stage, balanced transmission is preferred because it allows interference-free transmission of the useful signals even over long distances. The plugs are XLR or TRS plugs (TRS=Tip, Ring, Sleeve). Here, higher studio levels are used.
In addition to ground and the wanted signal (A), there is another wire that also carries the wanted signal, but in inverted polarity (B). When summing the signals A+B, the polarity reversal completely cancels the useful signal, leaving the interfering signal. The interfering signal can then be removed via an electronic circuit so that only the useful signal remains. This requires appropriate electronics in the unit, which may or may not be present. You have to look in the manual of the connected unit.
The preferred connection type in the studio is definitely a balanced connection, BUT ONLY IF the connected devices support it.
Other interesting articles around that topic
Why do my keyboards sound thin and weedy with some preamps but not others?
https://www.soundonsound.com/sound-advi … not-others
Q. Is there a better balanced-to-unbalanced cabling solution?
https://www.soundonsound.com/sound-advi … g-solution
Design of High-Performance Balanced Audio Interfaces, Bill Whitlock – Jensen Transformers, Inc. (Edited By Rod Elliott)
Interesting, but technical: https://sound-au.com/articles/balanced-2.htm
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14