Is a guy wasting his money buying inefficient speakers?
No. There is a lot more to speakers than this. Distortion. Dispersion. Driver integration. Compression. I have heard 83 db sensitivity speakers that play much louder than 91 db sensitivity speakers even if you drive the 91 db speakers with the same powerful amp that the 83 db speakers demand....a lot depends on Xmax and thermal compression. Many high sensitivity speakers with very light weight cones and long voice coils in small magnetic gaps (aka cheap drivers) will distort and compress very quickly.