EFFICIENCY

I have A Classe amp rated at 100 watts per channel into 8omhs and 190 watts into 4omhs.I am looking at two speakers,one has an efficiency rating of 86 and the other 90.

Assuming both speakers are rated at 8 ohms, the 86 db rated speaker would put out 106 db at full 100 watt output on the amp. The 90 db speaker would put out 110 db with 100 watts. Note that 10db = twice as loud. so 110 db is twice as loud as 100 db. Also, the 106 and 110 db speaker output would be at 1 meter from the speakers.

How important is this difference in the final sound quality?
Pegasusxls

Not important at all to the sound quality. Power and efficiency specs have no more to do with sound quality then gas tank size and gas mileage ratings have to do with automobile quality.

Cheers,
John

Are you just thinking out loud Pegausxls?

No one here can make purchasing decisions for you. How much better, and how much you want to spend are personal choices that only you can make.