Perhaps, in addition to transmitting the power better, they also serve as a filter and compensate for and clean up the grunge of miles of cable that end up at the wall and keep it clean from conditioner to component. After all is said and done, audio is transforming electricity (energy) to mecanical energy (speakers ad sound). Garbage in - garbage out. Bottom line, I believe; and the acid test, my wife can tell when I put in new PC.
