Interesting story: I bought a new receiver to replace my old Yamaha that just died, and used the new Audyssey auto speaker setup, the receiver kept telling me I had an error with my front left speaker. Yet, sound was coming out of it just fine, and an ohmeter confirmed it had an resistance of 4 ohms.
After some debugging, I opened the said speaker, and found that the magnet attached to the tweeter (by nothing else than magnetism), had detached itself from the tweeter and grafted itself onto the magnet of the lower speaker, messing with the sound somewhat.|
I just put the magnet back where it belonged, and the sound setup completed.
I'm just impressed that Audyssey was able to detect the subtle sound difference due to that magnet in the wrong place, and that it reported it back to me :)