I was leaving my Mono Extremes on 24/7 because Klaus said it was best.
Then I worried that I am wasting electricity, so I stopped doing it. I thought, "maybe I will be able to tolerate the decreased performance, and save a little money."
But since I stopped, I've never noticed a difference. None. And, I am one picky audiophile mofo.
I would be interested if anybody else has tried this and noticed any change.
Disclaimer: I listen to my stereo every 3 or 4 days. Maybe the caps don't have time to power down in this timeframe. When I have left the Extremes off for extended periods (more than 2 weeks), I have indeed noticed a decrease in performance when they are first turned back on.
Best of luck,
Hukk