We've checked 5K work with Galaxy s10 over USB c-to-c cable directly.
However, we need more tests with other Android devices.
We don't provide c-to-c cable, but c-to-A cable only.
We think USB C Android Smartphone users already have the c-to-c cable.

Great, thanks. And my last two questions? Will the wired connection only draw power from the connected smartphone instead of the internal 5K DAC battery? And will the app control the 5K DAC via the USB connection instead of Bluetooth (to conserve the phone and 5K's battery life)? 

Actually it's normally the other cable we have.   Most phones ship with a Usb A and most people don't have a C to C cable.   If your offering to let us use Usb from the phone throw in a decent C to C cable over the A to C

@B0b:
We can provide both options for that:

• 5K internal battery mode
• Smartphone power supply mode 

And the app works over the Bluetooth LE link only. It's LE(Low Energy) link, and the power consumption isn't that much concern.

Thank you!

If you have any USB C device, like the latest laptop or Android smartphone, you probably already have USB c-to-c cable for them.
In that case, you can share and use the existing c-to-c cable for 5K DAC.

On the other hand, if you don't have any USB C device, you probably have no c-to-c cable, and you don't need to have a c-to-c cable.
But you will need a c-to-A cable for your devices.

Anyway, we'll check which one is the best option for 5K.

@Qudelix

Having those two power modes for wired connection would be great, thanks. I think 'W' is right about the cable though. Almost all modern smartphones come with a USB-C to A cable, not C to C, so we would have to buy an extra adapter/cable to use the 5K DAC with our devices. As the 5K is primarily a device for mobile use on the go, including a USB-C to C cable would be much more useful for most users. Also, as the majority of people will already have a USB-C to A cable from their smartphones, they can just use this anyway if they want to connect the 5K to their PC for example.

@Qudelix

On the subject of the cable, how will the 5K DAC be charged? Using the included USB audio cable and a detachable power adapter? Or a separate one-piece power adapter with charging cable permanently attached?

I think it's only Google who supplies c to c. Everyone else, as far as I know does C to A. If it's possible, c to c cable would be really great.