I have a 5.1 setup consisting of two front speakers, a center speaker, two surround speakers, a subwoofer, and an Amplifier. Here are the Model #s:Front: Polk RTI A7Center: CSI A4Surround: RTI4Sub: VDR-12I'm not exactly sure what the knob on the back of the subwoofer does, but it's halfway between Direct and 80 Hz. If I turn it more to the right then the Sub goes to 80 Hz.. If I turn it more to the right of that, it reaches 40 Hz. Any idea where that knob is supposed to be? The Auto On/Off switch is also set to Active.I also went into the Auto MCACC in my Pioneer VSX 9130TXH. It ran through the setup but it determined I didn't have a Subwoofer, despite that it's plugged in and connected properly. I did some investigating on Google and realized that it's not working because the Center and the Front Speakers have been set to Large. Are these models considered "Large"? I could get sound from my Subwoofer if I set them to "Small" but I sort of feel like I'd be losing sound quality doing that...Last question. I went into the Manual MCACC and there are a few options I'd like to ask if it would be better if they were turned on. One of them is called X-Curve which is currently set to off. Another in the THX Settings is called Loudness Plug. That's also set to "Off". The X. Over is also set to 80 Hz so I'm not sure if I need to do anything with that...Some help would be much appreciated.