Matt, I only have one subwoofer. The Avia CD allows the user to match each channel with it's sub. (assuming you have a subwoofer for each channel) Since I only have one subwoofer they say to just match it with the front left. My problem is I can't get the sub or bass test tone level to match the tone coming out of the left front speaker. I have the left front set to 75 db. I can NEVER get the bass tone that low. Even if I shut the sub clear off. The bass coming from my main floor speakers ( 12" woofers) is around 85 db even with the sub level on the reciever set as low as it can go. Avia says the sub level should match, the mains evenly.