I had a 1984 vintage Yamaha integrated amp driving my KEF Q70's.
The Yamaha was rated at 75 or 80 watts per channel. The KEF's was rated for 10 - 150 watts.
In 2001, I was listening to Cleveland playing the end of Pictures at an Exhibition on Telarc and the Yamaha had a clipping event that nuked my KEF tweeters (back then, they were $125 each). After ordering new tweeters and carefully replacing them, a couple of months later, the same thing happened again. So, now I'm out 500 bucks in tweeters and an evening for each replace session.
My solution was to purchase a 4B-ST. My particular 4B-ST is rated at 288 watts for one channel and 289 watts for the other. The KEF's are 6 ohm, so best guess is I'm putting 430 watts on the KEF's. I can listen at volume levels that are insane and I've never had an issue.
So, I'm in the camp that more power is better.
As always, trust your ears and your mileage may vary...