[MarceFX]

That was for @Kyle1125

You need to run either:

a) an external TvHeadend server with that tuner on a RPi, Intel or AMLogic LibreELEC Box. Even then I'm not even sure the tuner will work on a AMLogic LE Box.

b) Run whatever TV Server Software comes with that USB Tuner on an External Intel machine and then download the corresponding Android HomeFree TV App. Even then I'm not sure that App will work on Android TV. If its a tablet App expect trouble.

Please read the PVR Wiki.
I seriously doubt you can Plug N Play that USB Tuner into the Mi Box.
The Mi Box's Android/Linux Kernel will not have the required USB Tuner driver support. In fact I know of no USB tuner support on the Mi Box at all.

Custom Firmware would be needed. But that's impossible because the Mi Box's Bootloader is locked down tight.

Ok, sorry for the misunderstanding. After a little more reading, I guess you're right, so I'm going to try another approach. I have a Windows machine acting as a server. I will install a TVHeadend server on a Linux virtual machine and plug the USB tuner into it. Then I will use the TVHeandend Live TV option on the Mi Box. I know it's a tedious workaround, but I like to have everything under the same input on the TV and with only one remote.

@MarceFX No you didn't do enough reading. It quite clearly says you need a PC to connect the AVerTV Volar HD 2 to and then you can view it on an Android device. Nowhere does it state you can connect it directly to an Android device. Time to educate yourself on what a backend and frontend is.

You're totally right. Sorry about that. I guess I got excited too soon... So, as I stated before, my approach will be a different one. Also, having my own TVHeadend server will let me reorder channels on the backend, since Android TV just lets you turn them off/on.

Thanks for your putting up with my questions!