The issue of 4ohm versus 8ohm is too simplistic. For example, my valve amps really rock with some (but not all) of the 4ohm Thiels, and drive Martin Logans beautifully, but don't do much with the 8ohm Silverline Sonatina. If you just look at impedence and sensitivity then the Thiel 1.5 should be as hard to drive as the Thiel 2.3 or even the 3.6 - but try it and you will find the 1.5 is actually very easy to drive.
4ohm and 8ohm speakers?
I know that 4ohm speakers are very hard to drive comparing to 8ohm speakers. So, my question is why some speaker manufactures still make 4ohm speakers? They stil make it because 1. 4ohm is easier to design? 2. 4ohm speakers are cheaper to build? 3. 4ohm sound better than 8ohm? or.... Thanks a lot