I just bought a couple of used Klipsch KG .5 bookshelf speakers (rating Impedance 8 ohms). I measured the resistance and I got 3.8 ohms. I thought something was wrong with these speakers. I know that Impedance rating is not the same as the resistance measured with an ohmmeter, but my understanding is that, normally, that reading would be about 2/3 to 3/4 of the speaker impedance rating (all my other speaker's rated 8 ohms their resistances varies between 6 and 7 ohms).
So I measured the resistance of my other Klipsch bookshelf speakers, two SB2's rated also at 8 ohms (which I bought new but I did not use much). To my surprise, their resistances were 3.8 ohms. My questions is, why for the same impedance rating, Klipsch speakers differ so much from my other speakers (and from the general rule)? Are they 8 ohms or, in reality, just 4 ohms? should I be concerned about my amplifier (set at 8 ohms) using these speakers? Thanks.