Remember, it is not only the raw power output specification that matters. Impedance matching of components in the amplification chain (preamp, phono preamp, and power amp) and slew rate are critical. Assuring the amp can handle the low impedance spec of the speakers is also critical. Impedance matching affects sound quality by permitting optimal power transfer which results in less distortion, a clearer sound, more impactful bass, and improved staging over a mismatched system. Slew rate, or how quickly an amplifier reacts electronically to rapid changes in input signal impacts distortion and dynamics in compositions with fast changing and dynamic passages/phrases. Finally, amplifier quality has an effect. My most recent experience in moving from a respected but vintage 300 WPC amp to a 105 WPC modern high quality integrated was significant improvements in all areas of SQ and no losses, including dynamics, staging, and image density. It just so happens the more modern integrated has a higher slew as will as modern design and better build. Two caveats:
1: specification are for designers: use you ears.
2: in general, I agree in the most part with all who stated greater power provides more musical authority … most of the time … but other factors enter into the game as is my experience with my recent change .