So, for anyone reading this…
I halfarsedly decided after reading this:
that nothing bad would have come from following my initial intent as in the title of this thread.
And what do you know, after a split second blink of the PEAK red-led of the HI-Z input I just have a continuous USB white-led blink (which, to my understanding, occurs when the host device doens’t recognize the UR12, but how can a wall do that?), and the device seems to be working normally: headphones in, I was able to hear my SM-57, perfectly amplified.
Sure, I did only try the thing for a second, but still waiting for somebody to prove this dangerous, I will keep at it and keep y’all (trying to do something similar) updated, when I make further attempts.