Why does my system sound better??

I unplugged my stereo to change back to my old speakers. Old speakers sounded better than I remembered. I unplugged stereo again and put back original pair and they sounded better than I remembered. This is not a scientific. My question is by turning off ones stereo system do you degauss the power cables in some way. I have a PS 1000 power plant but it does not have the degauss software. I do leave my stereo on all the time. Mike