Why are speakers efficiency/ohms different?

KrazyMofo24
KrazyMofo24 Posts: 1,210
edited August 2006 in Speakers
What are the benefits of having a lower impedance with more expensive speakers like the Lsi's? Also it seems the more expensive the speakers for Polk the lower the efficiency.
Setup:

2 Channel: Vienna Acoustics Mozart Grand, T+A P 1230R, Primare SPA21, Oppo BDP-105
PC: Vienna Acoustics Haydn Grand, Cambridge Azure 650A v2 , Peachtree iDAC, Denon DVD-3800BDCI