Have tried wading through this thread, and haven't seen ProAc mentioned. Why?
If you need a range of speakers that sound good with all Naim amps., and which were designed around valved amps., present a benign load and are of reasonable efficiency (88/89db), these are they.
One caveat; I and acouple of friends have only tried the older Response range (3, 3.5. 4) and Tablettes with 140, 250, 135s, Naits. It may be that design parameters may have significantly changed, but within the terms of reference declared (suit Naim, other amps, widely known and with a wide range), these should be considered.