Subwoofer to Receiver

[DGS12]

I am having trouble connecting a subwoofer to my receiver. The subwoofer originally came with a budget friendly surround sound system. The receiver is not the original included in the set. The subwoofer (Samsung) has only speaker wire attachments. The receiver has a "pre-out" plug spot.

I ran the speaker wire into a phono-plug and plugged that into the pre-out on the receiver but that is not working.

 

[Harald Kapp]

The pre-out (preamplifier output) is intended to be connected to a power amplifier input.
The speaker in is intended to be connected to a power amplifier output.
The missing element here is the power amplifier. Without one you will not be able to use the subwoofer.