We should reject hard-to-drive speakers more often

Yes, the 705s are not that hard to drive. But whether the speakers were sensitive or not was not the issue. Did I like the sound? I know two people who have Maggie's and 400 watts in each monoblock to drive them. They love them.  I see no reason to consider the fact that a speaker is hard to drive as a negative in and of itself. If you don't have or can't afford the power to drive them, then sure, it's a factor. 

@brev 

This is why it makes a difference: the harder you push the amp, the more difficult the load, the more distortion the amp will make. The other thing to consider is that not all really high powered amps are all that musical- its pretty well known that smaller amps tend to sound better.

I suspect you're using the same amp since both the speakers you mentioned are fairly easy to drive. But consider that if 100 Watts won't do it, you'd need 4 to 8x more power to do the job and as you point out, that can be expensive.

Also keep in mind that while the ZU is easy to drive, its not the only speaker that is meant to be easy to drive and there a number that IMO are also better sounding (while also being more efficient).

@atmasphere  The question for me is not whether the sensitivity of one's speakers matters in terms of integrating them into a system. Obviously it does. Nothing you are saying is new to me. The question is whether low sensitivity speakers are bad and they should be avoided. I think that's silly.  That is just a silly as if I said from my experience the high sensitivity is bad. That a speaker is difficult to drive just means you need to get gear capable of driving it. I think the great majority of people who own such speakers have got suitable power for them. 

That a speaker is difficult to drive just means you need to get gear capable of driving it. I think the great majority of people who own such speakers have got suitable power for them. 

Of course that is very true. But like I mentioned earlier, if it were a simple thing to have the speaker be the same but otherwise higher impedance/easier to drive, it would be instantly smoother and more detailed both at the same time since the amplifier would be lower distortion.

This is audible; Steve McCormick makes a very competent solid state amplifier that can easily double power into 4 Ohms as opposed to 8 Ohms. The Anticables guy makes a device called the ZERO that is an autoformer that allows you to drive a 4 Ohm load while the amp sees an 8 Ohm load. He has a letter from Steve that states while Steve's amp can easily drive 4 Ohms, it sounds better driving the same load through the autoformer. I'm sure the autoformer has losses and the like; its pretty good bet that if it were not needed the result would be even better.

That does indeed read like a good bet Ralph.  

Don't know how to explain it; driving our North Creek crossovered B&W Matrix 801 S2 speakers (87dB sensitivity, nominal 6 Ohm with benign phase angles and amplitudes) with only our 100 watt monoblocks (2x6BL7 + 4xKT77) sounds both better...and louder!...than driving the woofers with a Jon Soderberg modified Threshold Stasis 2 (~225 watt/ch.) and the tube amps driving the midrange and tweeters. 

I chalk it up to coherence tricking my brain into thinking it's louder...are there decibel meter apps for smart phones?  No need for responses to that...Google here I come.

Having recently place the Vandersteen Sevens in our Listening Room.  83.5db.  Never would have thought to pair them up with a SET 28wpc stereo amp but there you go, drove the hell out of them.  So you need to try things in order to find what will work in your system.

Happy Listening.