The JansZens, barring anything unforeseen, will be my last speakers. Their sensitivity ranges from 87dB to 90dB depending on how much you turn up the bass and tweeter controls on the back. I am probably somewhere in the middle then.
The 25 watts gives me all the sound I want. The crossover between the dual woofers and the dual ESL panels in each cabinet is a simple first order design and the overall load is very benign. These are easy on the amp. I think that is because the panels are pretty small and the overall impedance range is narrow. I'm running on the 8 ohm tap.
My current room is small (13' x 12') and very quiet so I don't need to push things much. The amp will however give out before the speakers will. Unlike some other ESLs these speakers can put out some pretty firm output with nice punchy bass.
As to the sound I would say it is extremely even and flat all the way down to 30Hz. All the ESL virtues are at play: midrange to die for, clarity, transparency, and timbre accuracy. The bass woofers are the best example of seamless blending in any hybrid I've heard. The woofers are also very fast and very tight. No additional damping is needed. The crossover is at 500Hz, just about the middle of a piano keyboard. When I listen to solo piano running up and down the keyboard I simply cannot detect any cutover or change in timbre. This to me is the acid test for a hybrid.
Before I bought the Torii I thought pretty highly of these speakers. Now with about 2 months break in for the Torii under my belt these sound like I gave them a $3k upgrade. Oh wait, I guess I did.

Good speakers should reveal any change in the system and reward you if the change is positive. I had a high quality SS amp before the Torii that really didn't have any sonic faults other than being SS. The Torii added, well, you know. These speakers are worth their cost.