The high impedance is because the speaker's sophisticated crossover uses a resonant circuit to boost the bass at about 80HZ. In order to do so, a paralled resistor, capacitor, and inductor are added to the woofer circuit. The sonic effect is an increase in the output of the woofer at low frequencies (though not appreciably below 80 HZ), but the electrical result is a higher impedance through the circuit than standard crossovers that merely roll-off the high frequencies that are being fed to the woofer.
LS3/5A vs. LS3/5A
I have owned Spendor LS3/5A's for 20 years, and always heard that all LS3/5A's sounded pretty much the same. Yet I have also heard that the speakers have been improved somewhat over time, so my curiosity got the best of me and I purchased a 3 year old pair of the Rogers. I was quite surprised to find that, IMHO, the "old" Spendor's sound much better than the "new" Rogers. While they obviously have much in common, the difference between the two was not at all subtle. The Spendor's are more transparent, throw a larger soundstage, and do a better job resolving inner details. In short, they are better at what I have always identified as the main strengths of the LS3/5A. Any comments on this from those of you who have experience with this speaker?