If I buy a receiver like the Marantz SR 7200, how do I ensure that my subwoofer is playing the low bass frequencies, both those of LFE channel and the plain old low bass of stereo CD's. Do I have to switch stuff around? This doesn't make sense. From some posts here, it sounds like when you set your mains to SMALL and connect your sub to the LFE, you might not get the sub reproducing the bass from stereo CD sources? I'm confused. How does it work?