Can I connect subwoofer line to my amplifier’s regular connection?

I bought a cheap Sony speaker system and the connector will not fit my Sony amplifier’s subwoofer “slot”. It’s a one line input.

Hold on everyone: First, you said two line connection. Is this two RCA outputs or a regular speaker-level speaker wire?

I suspect that it’s a line-level input on the sub.

So ok, if the subwoofer has a standard RCA input connection, then that means it’s a powered sub.
If the sub has regular speaker-level (speaker wire) inputs, then that means that it’s a passive sub, meaning that it does not contain an amplifier itself. This is what you need to figure out first.

If it has standard RCA inputs (on the sub), then you can just use one side on the input. Run your rca output from your receiver to the rca input on the right side of the sub. It doesn’t matter because subwoofers are mono anyway.

If your subwoofer has regular speaker-level inputs, then you can’t hook it up. Your receiver has a subwoofer “pre-out”, meaning that the receiver is passing a passive output to the sub. This output is designed to only pass the low frequencies, typically lower than 120hz, to the sub. This creates the proper balance for Surround Sound. In order to take advantage of this receiver output, your sub will need to have RCA inputs.

How to: Install a subwoofer and amplifier in your vehicle – part 1 of 2