No, because it's a USB to Optical Output. Optical does not have power run through it. However, the EC Mini has a separate USBC power input, according to the back of the unit. I am curios if I connect the USBC audio output to a dongle DAC if it powers the dongle like an Apple Dongle. THE Qudelix 5K it wouldnt matter so much because it has it's own internal battery. We shall find our when I get mine in!
After re-reading your post are you asking if you can just use the EC Mini as a sound card for audio output and input, while powering the EC Mini using just the USB C connector? Good question. I don't know. This is also cool because if it does audio both directions, with bluetooth receive and transmit, it can also be used as an outbound USB bluetooth receiver and transmitter for your computer as well.
Shanling, can you let us also know the USB Audio output bitrate and frequency 48K, vs 96k. If it's higher then that or if we are not able to change the USB Audio output it may have issues with a lot of USBC to optical converters. I believe there is a limit on how much optical can handle.