When your sub and receiver are working together, you'll hear the difference.

4. If you can't get a satisfying connection through the subwoofer output on your receiver, is there any other way to hook up your subwoofer?
Since only high-end receivers give you a preamp-out/main-in option, the only other alternative for most people is to use the front left and right speaker-level outputs.

Most subwoofers have speaker-level inputs and many have speaker-level outputs, too. Just hook up your sub from your receiver's front left and right speaker outputs using ordinary speaker cable. This will be a full-frequency signal, but the sub's built-in filter will block the higher frequencies. Then, connect your stereo speakers via the subwoofer's speaker-level outputs. Your sub will pass on the unfiltered, full-frequency signal. If your sub does not have speaker-level outputs, you can parallel wire both the sub and stereo speakers from your receiver's speaker terminals.

Many would argue that wiring your subwoofer with a speaker-level connection would introduce unwanted noise into your low frequencies, and this may very well be the case. This method should only be used if you (for whatever reason) can't get a satisfactory line-level connection through your receiver's subwoofer output.

Did you get all that?
PHEW! Well, I guess if managing your bass was easy, everyone would have crisp, rich low-frequency tones and perfectly balanced sound … but the reality is, most people don't.

Once again, the key is making sure your receiver and subwoofer are working together in a sonically symbiotic relationship. Check your receiver and subwoofer manuals carefully for details and make your connectivity decisions accordingly. If the pertinent information is not provided in the manuals (which is often the case), contact the manufacturer directly. If you're adding a new sub or receiver to your system, you should pay close attention to bass management issues before you buy.