I used Primaluna 36 watts to drive 88bd Salk Songtowers with great ease.Then traded up to 70watt Primaluna Evo 400 and found it didn't really make much difference in the ability to drive the Salks but sounded better.
Then I bought 93bd Tannoy Turnberry GR and that made a big difference in detail. All these subtleties came through.Will never again buy a speaker of even average efficiency.