The USB cable that ships with the UFX+ is ideal. I was having issues with ground noise coming from other USB devices through my motherboard and I just solved it by adding a Sonnet Allegro USB 3.2 PCIe card and using a Vital USB to USB C adaptor to have a dedicated high bandwidth connection for the UFX+. It's running flawlessly on this set up and there is no ground noise any more.

Its documented in the manual.
Yes, but then the amount of channels is being reduced to 30; all but MADI, compareable to UFX II.

In the hi-fi sector, customers are unfortunately all too often ripped off in the worst way. All you need is a solid cable, with good shielding and solid connectors. So far I have had very good experiences with Lindy cables. Their USB3 Premium cables cost a little over €20 and have triple shielding. More is not necessary, so you just throw money out the window.

Normally, a well-shielded USB3 cable up to 3m in length should be quite sufficient. Only in stubborn cases (ground loop problems) or if you need to bridge longer distances than 3m, USB3 extensions on optical basis are required. Search the forum, Matthias Carstens (MC), has written something here in the past about the various USB2 and USB3 based solutions.

If you really have so much money left in your petty cash that you had considered buying such expensive cables, I would rather put the money into buying an ADI-2 DAC or even better an ADI-2 Pro FS R BE to refine your setup a bit more. The ADI-2 DAC/PRO offer not only excellent quality (see technical specifications) but also very nice, pleasant features for monitoring with monitors and headphones. At this point the money would be much better invested.

See here how nicely ADI-2 Pro/Dac integrate into your Studio.
https://www.tonstudio-forum.de/blog/ind … our-Setup/

Especially useful the ADI-2 Pro, because it has
- analog inputs
- two analog outputs
- digital outputs (AES, ADAT)
- you can compare easily two different phones (ADI-2 DAC only has one phone output)
- it supports SRC (sample rate conversion) if you need to integrate devices with a fix / different sample rate
- Usual Reference Levels that you find in the studio (ADI-2 DAC has levels that you find more in HiFi)

I really like the high quality and features like:
- dynamic loudness
- slow ramp-up of volume when pluggin in phones and when switching between monitors and phones
- Auto Reference Level Settings
- Excellent Troubleshooting functions for digital audio connections in the State Overview
- now with extended remote even for the ADI-2 Pro

Worth to consider if you want to spend some more money.