So if I have 90 db/w/m speakers with my 100 wpc amp, I'm OK. And if I have 88 db/w/m speakers with my 200 wpc amp, I'm wrong? Not logical. Give actual reasons.

Power in amplifiers means high cost and lower quality incresing the power.

Sensitive speakers over 93db/w means less regular frequency response and higher cost not corresponding better sound.

Loudspeakers less sensitive than 90 db means more power into amplifiers with increasing cost before quality.

Magnepan speakers are probably the best speakers for the money and they're rated at 84db and a 4ohm load.

Alternatively, Avantgarde Duos and Trios are some of the best speakers I heard at any price and they're 101db and 109db respectively at 19ohm load.

How do you reconcile that?

In my "real world", I have balanced the cost and quality of my amps and speakers. If I use your assumptions, I should have chosen different, more efficient speakers. And I should have partnered them with a different, LESS powerful amp, on your assumption that less power correlates with higher quality.

I understand your fuzzy general point - but I don't think it relates well to the real world of the MANY product choices in the market, and how they work with each other.

Example: I listen to speakers A, B, and C in my price range. I like C the best. Oops, it's only 88 db rated. So should I choose A or B instead? I say no.

I agree with Bill, you balance the speaker/amp budget and consider the strengths and weaknesses of each when putting the system together. Saying to avoid this or that will eliminate many superlative alternatives, IMHO.

The speakers I enjoy a lot tend to like lots of power and damping. Luckily for me, I can afford amps that cost one to two times my $3500 Vienna Acoustic speakers, so I love the system that I get when I throw in a Jeff Rowland or Conrad Johnson amp that matches up well.

Dave

Choosing what speaker to buy based on efficiency is like choosing a new car based on some theoretical "perfect" tire size. I don't think that I need to tell anyone that doesn't make any sense.

My Martin Logan CLS speakers are some of the most inefficient speakers ever made but with the right amp and set up of the speakers they regularly elicit goosebumps with ease.