What does "Clean power mean?" What does it sound like? What does it taste like? Why is it important? I hear "Clean power" when I walk into a mid-fi shop when a 17yr old salesman tells me about his wonderful Yamaha and Denon recievers, which make my ears bleed after inducing vertigo....but less then .00000001% distortion the salesman cries as I try to shove my keys into my ears.....If that is what "Clean" sounds like, I'll take my power dirty, please.
Seriously, my advice, get thee to every hi-fi shop in a 2hr driving radius and go listen. You're probalby new to the hobby, the only way for you to find out what type of sound that your ears prefer is from your own adventures, not vicarously through someone else.