* Signals seem to lose a lot of resolution as you get even inches away
from the likely source. The falloff (unsurprisingly) seems to be logarithmic/exponential — fast initial, slowing down as the distance increases. This doesn’t hold, strangely, if the signal source and e.g oscilloscope share a common ground. In that case you can pick up a 100kHz signal with surprisingly little distortion given the source at your toe and the scope probe at your finger.
* I’m using a Sony ICD-UX512 44.1/16-capable dictaphone I picked up retail for the recorder. For some reason it seems massively less susceptible to confusing interference.