Your listening notes are exactly why I've never bought KEF speakers (back in an age where I had disposable income and electronic means of correction weren't as easily accessible, nor were the measurements): I always found them to be too "polite", not engaging enough. I went with Focal (then...
Just nitpicking, but is there a reason why the text and the values are in the opposite direction in the DAC comparison graph? To read the text you need to tilt your head to the left, but that makes the values upside down ;-)
The reason for this seemingly erratic behavior of USB-C DAC's/dongles isn't the devices themselves, but the source device and its implementation of audio over USB-C. The USB-C standard allows either analog audio or digital audio. If the constructor of your device has chosen to implement analog...
I use a self-hosted instance of bitwarden (https://bitwarden.com/open-source/). For people using Home Assistant there's an official add-on (https://github.com/hassio-addons/addon-bitwarden)
I contacted the vendor where I bought it (on AliExpress), reply was to ship it back at my expense. As this would cost me almost as much as the device had cost, I didn't do anything further.
I recall doing a firmware update at some point, without negative effects. When the device eventually got in the state described above, I've tested it on several PC's, both with & without the driver, Windows as well as Ubuntu, no difference at all :-(
I have Focal Elear headphones, and their cable is incredibly stiff, heavy and long (3m). I've never been a cable believer, but ergonomically it isn't all that brilliant, so I went on the lookout for something nicer ergonomically, without spending audiofool money.
I stumbled upon Venture...
I have (visually) the same set from Dayton Audio (https://www.parts-express.com/Dayton-Audio-Sub-Link-XR-2.4-GHz-Wireless-Audio-Transmitter-300-580). For me it works well over a distance of ±5m, transmitting the subwoofer channel of my HT setup, with the added benefit of breaking up a ground...
That looks like a very worthy successor to the venerable Squeezebox Transporter and given the inclusion of a Raspberry Pi and Audiophonics' support of PiCorePlayer its not only a capable streamer/DAC, but also the center of a whole-house audio system :)