The above may be true as it relates to pre-outs, but a filter can also block signals from being sent to the sub below a certain point.
For example, I can configure my sub 4 different ways.
1. unfiltered
2. 16hz
3. 20hz
4. 24hz
I have mine set to 16hz, which means that any signal below that point is blocked.
You'll want to read your user manual to see which application applies to your receiver.