If the light is on, the cable is plugged in to both the sub and receiver, the cable is known to be good, the volume on the sub and receiver are both up, the receiver is turned on and the sub out is known to be good, and the music isn't some pansy flute, I'd say whoever passed those down to you hated you and blew the shite out of them before passing them down in order to make your life miserable.
BTW, there is no input and output on those subs. The two RCA connectors are in parallel. You can connect to either one.
