“What are the consequences (if any) in regard to the equipment when you inadvertently get into a digital loop and the equipment feeds back? Sounds like the equipment doesn’t like it, and neither do I. But it happens sometimes. I understand that the speakers are the most vulnerable link in the chain, but what about the rest of the equipment?”
There isn’t much that will fry speakers faster than feedback. Besides the discomfort and potential damage to your ears, any type of speaker or headphone is by far the most at risk during feedback. The way electronics work most devices are limited by the supply voltage of their power supplies. While they may go into extreme distortion during feedback (which, by the way, is usually what destroys the speakers), they aren’t going to harm themselves. There’s always an exception somewhere, but generally electronics are not significantly harmed by feedback, though it is best to avoid it. Digital feedback loops often produce a type of feedback that is inaudible and therefore pretty harmless even to speakers.