Originally Posted by

**denjo**
I have often been intrigued by how you determine the specific impedance of Harbeth speakers? Taking an example, the SHL5 has a 6 ohm officially published impedance. The impedance is very important since it determines how much power is needed from the amplifier to suitably drive the speakers. Generally speaking, a 60 watt amplifier (at 8 ohms) would be 90 watts at 6 ohms and 120 watts at 4 ohms. When I study the impedance chart (or at least try to), the impedance is represented as a curve which rises and dips across the frequency spectrum. Do you take an average across the board...