I built my own pair of speakers and I haven't gotten the chance yet to measure the impedance raiting on them yet. I figured my Sony STR-DE585 would be able to drive them. It handles 8-16 ohms. I figured these speakers would be 8 ohms, so I hooked them up as rears and after about and hour of listening to my music everything went silent. I went to the reciever to see "PROTECT" flashing in the display. My bad. I guess my speakers aren't 8 ohms. The unit was very hot. Whatever triggered it. Temperature protect or it realized the amps couldn't drive these...If that feature wasn't developed my reciever would probably be on fire right now. This is a very handy feature. Anyone ever had experiences like this? Any other cool features like this you know of? Please tell!