Originally Posted by nonesuch75
Quick question guys...I recently bought speakers with 6 ohms nominal impedance and 4 ohms minimal impedance. I am thinking of getting NAD's T747 receiver (60 watts).
Does the NAD have enough power to drive/support my speakers?
The size of your Room will have a large impact in terms of how well the T747 will work for you. In addition, depending on listening preferences and Sources, you might want more power.
What kind of Speakers are you using? As in addition to Ohms, there are things like the Sensitivity and Capacitive Phase Angle that might make using an AVR that excels with 4 Ohm loads more advantageous. However, more than likely, the T747 should be fine.
As to the original question, I am in complete agreement that it is a Design decision. Some Speaker Technologies are much less efficient and can dip below 1 Ohm. Such is the case with Martin Logan Electrostatic Models. It is only at the uppermost frequencies that the load is that low. And Speakers like the aforementioned Magneplanar which use Planar Ribbon or Quasi Planar Ribbons are comparably inefficient and low ohm. Moreover, Speakers such as Thiel which employ First Order Crossovers and are Time and Phase Aligned, present a challenging load.