@audiokinesis , thank you for oversimplifying. That helps.
@james633 , thank you for the feedback on this. I think I am getting the picture. High efficiency doesn't take as much power to move and at lower levels not as much power is being provided to the speaker as at higher levels.
@elliottbnewcombjr , I am actually not the one with the KEFs, that was @zlone . I am trying out a pair of Revel M126Be's. I like them so far, but after reading posts here in the speaker forum, I am questioning myself as to whether a higher sensitivity speaker would have been a better coice in the small room I listen in. My amp does not seem (to me) to be straining in 50 wpc. I know your opinion of triode versus ultralinear, and today I put another 5.5+ hours on them, and for the last couple of hours I went to 100 wpc ultralinear and I felt that female vocals took on a bit of an edge in that mode. I guess the final proof (or close to final) will come in about 20 more listening hours when I follow @soix 's advice and hook up my old speakers and see how I feel about the difference. As always, I appreciate your feedback. It is always welcome.