Watts, and clarity.

Is it still true that all other things equal in a stereo system, that watts do more to clarify sound quality, than watts to to increase decibel output?, or has newer technology changed this? I used to hear that it takes ten times the watts to double the decibel output "all other things in the stereo system being equal". This was back in the 80’s that I heard this. I also remember hearing that it took 24, 400 watt power amps to reproduce the sound of scissors snapping without cutting of the sound wave on an oscilloscope. Is this true?