> On a similar note...is anyone else here able to 'sense' when an electronic device is active in a room, despite there being no visible signs? Even with a blank screen, no static noise, and no telltale LED indicators--

Monitors emit a high pitched whine, so high sometimes that it's not even necessarily detectable as an actual sound. But the impression is unmistakeable. Yes, I can walk into a room, or sometimes just walk by a room, and instantly know if there is a monitor turned on. Depends on the monitor sometimes. Same goes with other electronic devices, although not all.