Here's the thing -- owning and Kensington SE and having heard the Yorkminster SE in my system, that 2dB extra efficiency and 6Hz bass extension of the latter makes a huge difference (shocking, even). The Kensington has the sweeter midrange, but it's hard to tell how much (if any) that gap would narrow with further break-in. I love midrange, so it was a tough choice.
That said, it's no wonder I use higher powered amps (250 W/ch Rogue Apollo tube monoblocks) on my Kensingtons. For my listening preferences (often quite loud, sometimes high dynamic range recordings) and room size (fairly large), that 93dB-95dB/Watt range defines a pretty critical zone; any less is quite hard for me to live with. I disagree with the notion that a 3dB difference is "hard to notice". It makes ALL the difference with speakers as resolving as the Tannoy Prestige, which will remain sounding musical at any level you can push (cleanly) into them, AND will easily reveal shortcomings of the electronics (that's their magic - just wish they were a bit more efficient and extended).
I've used restored vintage tube amps (Heathkit W5, Eico HF-87) of 20-35 W/ch on the Kensingtons, and the sound with the W5 can be sublime. BUT, at those power levels you'll have to concede on at least one of these 3 points: 1. Loud listening 2. Large Room 3. High Dynamic Range material. By point 3, I mean that you can blast modern compressed pop/rock/metal recordings as loud as you like on just 20-25 Watts...but you'll notice significant limitations when you switch over to classical. I definitely noticed such limitations at under 60 Watts/ch.
I prefer tubes to solid state; I got the Apollos because they offer tons of clean tube power at a reasonable price, and offer superb build quality, service, etc. I've also heard the Rogue M180, which sounds very close at half the price (with KT120 outputs). Rogue gear can sound a bit more like (good) SS with the stock tubes; for my preferences I "fixed" that by rolling in RCA blackplates and KT120. Again, the Kensingtons are so revealing of upstream gear and individual tube swaps - and that's where tube gear pays HUGE dividends, by allowing you to fine tune the system to your preferences & needs.
First decide what power level you *need*, then choose between tube vs. SS, then choose the model.
