So, I've found a way to mess up V20's impedance detection in a new way that I haven't seen here.
I had an old pair of sports iems, Sennheiser CX680. Now, these come with an extension cord that has analogue volume control, a small wheel on it. The thing I do is connect my headphones to it (needs a very thin jack or would have to cut some plastic to gain better access to 3.5 jack) and as soon as I plug it in V20, I rapidly spin the wheel for 2-3 seconds. It goes to high imepdance always... You just have to be quick and spin it right after you've connected it.
Obviously, don't connect headphones when plugging it and you get a regular aux output. So, this thingy can trigger any of 3 modes relatively easily.
Keep in mind that my extension cord with volume control removes the right channel when pushed to max volume, perhaps it's this slight defect that is messing with V20, but I doubt it.
Additionally, you can set a certaint level on the volume wheel and limit how much power is going to your headphones at max 75 volume.