Here is some info on the current situation with Apple's Mac Mini 2018 and 10.14.2.
- USB 2 is not usable for audio on any port.*
- USB 3 is not usable for audio on the two USB-A sockets.*
- USB 3 works as expected on all USB-C ports using a USB-C to USB-A adapter**
If you use an USB-C to USB-A adapter and connect a USB 2 device it is internally connected to the same bus/hub where all the other USB 2 sockets are connected to - and thus won't work. You can gain basic knowledge about the internal structure and connections by using the Mac's System Report/System Information, USB. Connect your USB device and look where it is shown in the nested structure.
In clear words: there is currently no way to have a Mac Mini 2018 working without audio errors when using USB 2, neither directly nor with the standard USB-C to USB-A adapters.
But there is a workaround. Devices connected to Thunderbolt do not show audio errors as with the internal USB 2. So all you have to do is use 'external' USB. Two examples:
- A Thunderbolt 3 to PCIe enclosure (Sonnet, NetStore) with a simple USB PCIe card added. Of course that is kinda overkill unless you own such a system already and just have to add the USB card.
- A more simple Thunderbolt 3 'dongle' with a USB port. The one we tested also seems to be the currently cheapest one:
https://www.caldigit.com/thunderbolt-3/ … splayPort/
This device uses the PCIe bus of Thunderbolt and derives USB with its own USB chip, so is totally decoupled from the broken USB 2 in the Mac Mini 2018. Which is why it also doesn't show the infamous USB disconnect problem (USB hangs until reboot).
A word of advice: there are a zilllion cheap docks with USB, HDMI etc available, that often have 'Thunderbolt 3' in their name or description. These are NOT Thunderbolt 3 devices! To recognize real TB3 is quite easy:
- Thunderbolt 3 is mentioned on the package
- the USB-C connector has the Thunderbolt flash symbol on it
- the product description clearly mentions TB3 and 40 GB/s
- the display ports support 60 Hz, not only 30 Hz
- the price is above 100$
Here are some examples of NONE TB3 docks/adapters that won't fix USB audio:
https://www.amazon.de/sicotool-Thunderb … B07FCGFQJP
https://www.amazon.de/CableDeconn-Thund … B07B66LNRS
https://www.amazon.de/CableDeconn-Thund … B07BK4TRG8
https://www.amazon.de/UGREEN-Thunderbol … B077FZQS95
https://www.amazon.de/QacQoc-Thunderbol … B07KC5V3GR
This last one from QacQoc is presented as real TB3 solution, but on the second look it's a scam. The flash symbol stands for power (it's not the Intel flash). The first USB-C to USB-C connection is most probably a wired pass-through, violating the TB3 specification (but it's not TB certified anyway). The other ports are connected to the second USB-C and are therefore not derived from TB3.
Alternative to the CalDigit dock (not tested):
https://www.amazon.de/Elgato-Thunderbol … 07GS9XM54/
We are still continuing our tests.
* All USB 2, and USB3 in the two USB-A sockets, is derived from the Intel chipset, Device ID 0xA36D, Cannon Lake PCH USB 3.1 xHCI Host Controller.
** USB 3 within USB-C is derived from the TB3 chip, Device ID 0x15EC, a Titan-Ridge Thunderbolt 3 Controller.