Tis true. You can have a valve amp friendly 84db speaker (it just won’t go that loud) with simple phase angles and steady impedance and you can have 101db nightmares with a crossover that just demolishes any amp not able to deal with it.
While sensitivity is okay as a starting place, the exceptions are just too numerous to be safe.
Totally agree…the S12 Vivids on the end of a 500dr is great…lots of control although they are not floor standers…I love that grip…and control…
Just an observation.
PMC 25.23 are rated at 8ohms and 86.5dB.
Dynaudio Heritage are rated at 4ohms and 85dB.
However, auditioning with a SN3, the PMC presented a far more difficult load than the Heritages. It took 25.24 to match the SN3 capabilities, while the Heritages played very happy with the SN3.
Sensitivity is a terrible guage of driving difficulty. As a rough guide it’s often the only starting point but there are 84db tube amp friendly speakers and 98db real demons to drive out there.
PMC opt for high order complex crossovers. Dynaudio for low order simple crossovers. Totally different approaches. So the results don’t surprise me.
Nominal mpedance and sensitivity in themselves are not indicators of how easy or difficult a load a speaker may be. On the other hand tge Impedance curve, showing the variation with frequency, is significant, so, too is the degree of mechanical damping of the speaker drivers by the speaker design, which is something not normally known nor readily identifiable.
My SN2 hardly made twenty5 26 sound fully, I had to upgrade to 282 250 to let them properly breath. In theory SN2 and 250 have the same power, in practice they are totally different beasts. So it’s not just a matter of db/watt
No wonder, the SN2 toroidal transformer is rated as 400VA, while the one inside 250DR is a massive 1020VA one.
Finally got around to unboxing and installing the system in my small home office. Sounds underwhelming but things should pick up in the coming weeks. The room is small (12mp) but the low end is surprisingly lean.
*Update.
Top end has mellowed while the low end gained in strength considerably.
It’s not quite there yet, but I’m slowly regaining my grin 
Good times.
It’s good to hear that they are settling in nicely. Mine initially didn’t sound anywhere as near as good as the demonstrators but are now much better. It’s interesting that you chose the 23s for a small room. My room is about 17m2 and I chose the 21s. I’ve had the original 23 in the past, with a SuperUniti, but I wanted to stick with stand mounts this time around.
You don’t see the 21s on here much and I don’t think I’ve ever seen anyone using the PMC stands. They are a nice design and you can run the cables up the rear tube, which is damped internally. Their slope matches the speakers of course, so overall they take up the same floor space as a pair of 23s. It was hard to choose the colour. We’ve never had dark wood speakers, so oak was the easiest choice, but we went with the walnut as it’s less of a contrast with the black of the stands and grilles and I thought it would be good to do something different. The look has taken a bit of getting used to, but we are now very happy with it. It’s good to see a bit of enthusiasm for PMCs.
Another vote for PMC’s here, namely Twenty5 23i .
These are giving me a better sound in my room than ATC SCM 40 passive and active. I also think the 23’s are a better match to the room than Twenty5 26’s, which I had previously. 
I’m always admiring your beautiful home and impeccable taste, unmistakably British.
Those 3 pin sockets the British give away?
Three weeks have passed since firing up the system and for the first time I can really enjoy the PMCs and immerse myself in music. All the top end harshness mellowed while the down low got really tight and tuneful, as many PMC owners here predicted they would. I’m listening to full albums again, without fidgeting and hopping from artist to artist anymore.
Thank you Naim and PMC!
The adventure is only just beginning………….
PMCs are definitely on my shortlist when I change my X2’s. Seems many are happy with the 25/23 (i) which is where I would start. Would be driven by my Nova. I’m a bit of a sucker for transmission lines having had Rega Ela’s previously. They do have a certain va va voom
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