Yo debaters of efficiency:
Normally, I like highly efficient speakers. They give a wider dynamic range, and way more output with way less watts. This particular application, which is near field and low level, does not require a wide dynamic range, just the low end punch, which comes from having a good low frequency response. As a matter of fact, when listening at low levels, some compression may be necessary to avoid losing the softer passages.
In near field, because you are close, you get more punch becasue speaker is close. Any more, amplifier power is cheap and easily obtained, so you are not restricted to 10 WPC amps, like you used to be back in '60's when I built my first amplifier kits. There are lots of good 40-50 WPC amps that will work well when driving a speaker at close range, even if speaker is not real efficient. There are also lots of modular amps that are pretty good and dirt cheap. My experience with Dayton Audio BR-1's in near field with a Yamaha CR 220 receiver, 20 WPC, was that they sounded real good, produced adequate volume despite low efficiency, and they were solid and punchy sounding, with response down to about 40 Hz. Much better for range than a lot of "audiophile" speakers. They are better for instrumental music than for spoken word or vocal music, such as for opera. But. of course others who use different speakers may disagree, and they are certainly entitled to do so.
And good luck from that harmonious, but punchy old opera fan,