tape out

My question is this : I switched off the amplifier , even disconnected it electrically.. how is it possible that my rear speakers worked (the one connected to the blue jack here) I , of course, unplugged the Realtek from the pc to see if it could be the cause but not… Can an amplifier...

When I plug any cable to the tape out of my sansui 2000a, the volume decreases out of my speakers. Has anybody else had this problem on other receivers?