Selecting LFE+MAIN allows the low frequencies from all speaker channels to be output to the subwoofer. LFE + Main - The low frequencies output to the Subwoofer whether the speaker channels are set to Large or Small. Large sends that channel a full-range signal. LFE+Main generally refers to setting the mains to large and having bass directed to both mains and sub. When to use LFE+Main ? Just curious when does anyone use this and what benefit does it have ? I have dual in wall Def Tech subs on dual. As I mentioned in the video, with some content, running towers as Large and LFE +Main can.