My DIY subwoofer enclosure is almost done so I have a question concerning balancing it with my mains. I have just ordered the sound and vision setup disk and assume that it has bass frequencies on it. My question is this: Do i just play like a 40hz tone through the subwoofer and set the db level to match my other speakers using my radio shack SPL meter? If not, could someone direct me to a site that has the proper way to set the level of a sub? Thanks, Paul.